TweetFollow Us on Twitter

AS Performance
Volume Number:12
Issue Number:5
Column Tag:Applescript

Improving AppleScript Performance

Avoiding the AppleSloth blues

By Mark Alldritt

Note: Source code files accompanying article are located on MacTech CD-ROM or source code disks.

Why Is AppleScript So Slow, Anyway?

This is the question our customers ask most frequently, and one to which there is no simple answer. The reason given by Apple is that the Apple event mechanism used by AppleScript to communicate with other applications has serious performance limitations under System 7. In my tests, there clearly are limits to the number of round-trip Apple events you can push through the system per second. However, there’s something else wrong, apparently, because even AppleScript scripts which don’t generate any Apple events do not seem to perform as well as similar scripts written in Frontier.

This article provides a number of tips for improving the performance of your scripts. Depending on the kind of scripts you are working on, these improvements in performance may turn out to be dramatic.

Improving Compile Time Performance

Regardless of what script editor you are using, you are bound to get to the point where you wish scripts would compile faster. Here are some tips for keeping compile times as short as possible:

Buy Speed Doubler if you are using a PowerPC-based Macintosh. My customers have reported a 2 to 4 times improvement in AppleScript performance with Speed Doubler installed.

Keep the number of scripting additions to a minimum. Having too many scripting additions slows AppleScript’s load time, since it must process that many more files in the Scripting Additions folder. Also, more scripting additions means more event and class names must be parsed from 'aete' resources and added to the AppleScript symbol table.

A side benefit of keeping the number of scripting additions to a minimum is that you are less likely to run into terminology conflicts. This happens when a term is defined by two different scripting additions.

Split up your scripting projects. Use the load script command to load pre-compiled portions of your script project. If you’re using Script Editor, Script Wizard, FaceSpan or Scripter, it’s probably best to store your pre-compiled scripts in a known location so that you can use simple Load Script statements:

property lib1 : load script alias "My HD:Script Libraries:Lib1"

Alternatively, you can store your libraries in the same folder as your script editor, and load them with the following command:

property lib1 : load script "Lib1"

If you’re using Script Debugger, you can use its path to me handling to store your libraries in a folder with your script:

property projectPath :¬
 «property ctnr» of item (path to me) of ¬
 application "Finder" as string
property lib1 : load script (projectPath & "Lib1")

Once you’ve loaded your library, you can access properties and call handlers stored within it like this:

propertyName of lib1

handlerName(p1, p2, p3) of lib1

Don’t overdo AppleScript formatting. The formatted text feature of AppleScript is the only really good way to understand how AppleScript has interpreted your script during compilation. Unfortunately, the more formats you use, the slower your compiles will be. The slowdown is caused when your script editor is forced to cope with growing numbers of style runs as it displays your script following a compile. The answer is to keep the number of formats you use to a minimum.

This point becomes more important as the size of your scripts grow. For short scripts, it’s not really an issue, but for scripts larger than about 100K it can represent as much as a couple of minutes of the total compile time. A PowerPC-native script editor helps here (Script Debugger, Script Wizard), but it’s always going to be an issue.

Keep background activity to a minimum. All the script editors allow some level of background activity during compiles. If you keep this to a minimum, your compiles will be faster. Avoid having the Finder perform folder size calculations, turn off personal file sharing, etc. If you’re using Scripter, turn off its “allow background compiles” preferences option. This speeds compiles dramatically.

Improving Run Time Performance

Probably the most frustrating part of using AppleScript is watching its seemingly slow progress through your script. Here are some tips and ideas for making scripts run faster.

Install Speed Doubler if you are on a PowerPC.
See above.

Keep the number of Apple events your script generates to a minimum. Under System 7, Apple event performance is poor. A System 7 application can process at most 60 events per second, with typical performance more like 20-40 events per second. Reducing the number of Apple events will significantly speed up your script.

The most common mistake is to iterate over application objects using AppleScript. Instead, use “whose” clauses to get the server application to do the iteration for you. (Note: not all scriptable applications support this - complain to the developers and let them know you want full support for the “object model”.)

The slow way:

tell application "Finder"
 repeat with aItem in (items of first window)
 if name of aItem ends with ".temp" then
 delete aItem
 end
 end
end

The fast way:

tell application "Finder"
 delete (items whose name ends with ".temp") ¬
 of first window
end

The next error people commonly make is to repeatedly ask for the value of properties. For example, you might do the following:

tell application "Finder"
 repeat with aItem in items of window 1
 if name of aItem ends with ".c" or ¬
 name of aItem ends with ".h" then
 -- do something with .c and .h files
 end
 end
end

This script fragment gets the value of the application’s name property twice. A faster method is to get the name property once:

tell application "Finder"
 repeat with aItem in items of window 1
 set theFileName to name of aItem
 if theFileName ends with ".c" or ¬
 theFileName ends with ".h" then
 -- do something with .c and .h files
 end
 end
end

Avoid using AppleScript’s object-oriented features. AppleScript supports object-oriented programming to a great extent. I’ve found that handler calls within object instances tend to be slow (the first handler call is the worst). Use these features only if they are justified.

Use properties to store pre-compiled values. If there are values which are calculated once at the beginning of your script, consider putting these calculations into property definitions. By doing this, you cause the calculations to be performed at compile time rather than run time.

This technique can be particularly dramatic if you are using scripting additions to help with the calculations, since the Apple events used to invoke the scripting additions are generated at compile time.

Use scripting additions. Use scripting additions for complex list and text manipulation. The ACME Script Widgets and other collections of scripting additions offer tools for text parsing, tokenization, list manipulation and other functions. It’s almost always going to be faster to use a scripting addition rather than an AppleScript loop to work with these data structures.

Execute scripting addition commands within your applet’s process. As stated above, Apple events sent to other processes for handling are slow (20-60 events/sec); but events processed within the script applet are handled much faster, since they are dispatched without involving interprocess communications and process context switches.

So, in the following example, the current date command (which is a scripting addition command) is executed within the Scriptable Text Editor’s process rather than the applet:

tell application "Scriptable Text Editor"
 make new line at end of first window ¬
 with data (current date as string)
end

An improvement in speed would result if you did it this way:

set theData to current date as string
tell application "Scriptable Text Editor"
 make new line at end of first window ¬
 with data theData
end

If you are deep within a tell block, you could deal with the problem this way:

tell application "Scriptable Text Editor"
 ...
 make new paragraph at end of first window with ¬
 data ((current date) of me as string)
 ...
end

Use the right tool for the job. Sometimes you can get dramatic speed improvements by switching tools. For example, if you’re doing text manipulation, consider using MacPerl, or BBEdit, or a special-purpose scripting addition. If you have several tools available, try using each of them to perform time-consuming parts of your script. See which one is best suited and performs best.

Use the right object accessing method. The Object Model is a powerful thing, and offers great flexibility for the script writer. The problem is that it allows you to easily create object specifications that can be very difficult for the server application to resolve.

You can sometimes improve performance greatly by changing the way you access objects. For example, text editors generally maintain internal data structures to help them identify the beginning of lines. As a result, line-based object specifications are resolved much faster than word- or paragraph-based specifiers, because the application can use the data it already has to speed things up.

Try using different ways of forming your object specifiers and see which ones are fastest.

Code time-consuming logic in OSAXen. As a last resort, you can code time-consuming portions of your script as a scripting addition. MacTech Magazine 10.1 featured an article on just this subject, and you can look at it online at http://web.xplain.com/mactech.com/Articles/Vol.10/10.01/
Extend-Applescript.bhtml. Documentation on writing scripting additions can also be found in Apple’s AppleScript Scripting Additions Guide.

The Final Frontier

The applets (standalone AppleScript applications) produced by Script Editor, Script Debugger, Script Wizard and Scripter all rely on the standard applet glue code provided by Apple. This glue code provides a framework in which your script executes. The standard glue code attempts to be a really good MacOS citizen. To this end, it yields the CPU to other processes very frequently. One way to improve the performance of your scripts is to write your own glue code, and yield the CPU less frequently, or possibly not at all. This change, depending on the frequency of yields, can cause speed improvements of up to 25%.

The Future

The future of AppleScript is quite bright. Following a period of almost non-existent support from Apple, there is to be a new version (1.2) released sometime this year. This new version will be PowerPC-native, and is expected to offer performance comparable to that of Frontier. Beyond the 1.2 release, there’s Copland. There is reason to expect that under Copland, the AppleEvent Manager will offer dramatic performance improvements; supposedly, Apple events will be dispatched directly to your handlers, not to your app’s event loop, thereby removing a serious speed bottleneck. And, there are rumours of a completely re-architected post-Copland AppleScript 2.0. In the meantime, AppleScript continues to prove its worth, and the techniques in this article should help you see some script speed improvements now.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Adobe After Effects CC 2018 16.1.3 - Cre...
After Effects CC 2018 is available as part of Adobe Creative Cloud for $52.99/month (or $20.99/month for a single app license). The new, more connected After Effects CC 2018 can make the impossible... Read more
Adobe Audition CC 2019 12.1.4 - Professi...
Audition CC 2019 is available as part of Adobe Creative Cloud for as little as $20.99/month (or $9.99/month if you're a previous Audition customer). Adobe Audition CC 2019 empowers you to create and... Read more
Adobe Premiere Pro CC 2019 13.1.5 - Digi...
Premiere Pro CC 2019 is available as part of Adobe Creative Cloud for as little as $52.99/month. The price on display is a price for annual by-monthly plan for Adobe Premiere Pro only Adobe Premiere... Read more
Navicat Premium Essentials 12.1.25 - Pro...
Navicat Premium Essentials is a compact version of Navicat which provides basic and necessary features you will need to perform simple administration on a database. It supports the latest features... Read more
Sketch 58 - Design app for UX/UI for iOS...
Sketch is an innovative and fresh look at vector drawing. Its intentionally minimalist design is based upon a drawing space of unlimited size and layers, free of palettes, panels, menus, windows, and... Read more
ClipGrab 3.8.5 - Download videos from Yo...
ClipGrab is a free downloader and converter for YouTube, Vimeo, Facebook and many other online video sites. It converts downloaded videos to MPEG4, MP3 or other formats in just one easy step Version... Read more
Dash 4.6.6 - Instant search and offline...
Dash is an API documentation browser and code snippet manager. Dash helps you store snippets of code, as well as instantly search and browse documentation for almost any API you might use (for a full... Read more
FotoMagico 5.6.8 - Powerful slideshow cr...
FotoMagico lets you create professional slideshows from your photos and music with just a few, simple mouse clicks. It sports a very clean and intuitive yet powerful user interface. High image... Read more
Civilization VI 1.2.4 - Next iteration o...
Sid Meier’s Civilization VI is the next entry in the popular Civilization franchise. Originally created by legendary game designer Sid Meier, Civilization is a strategy game in which you attempt to... Read more
Skype 8.52.0.138 - Voice-over-internet p...
Skype allows you to talk to friends, family and co-workers across the Internet without the inconvenience of long distance telephone charges. Using peer-to-peer data transmission technology, Skype... Read more

Latest Forum Discussions

See All

Lots of premium games are going free (so...
You may have seen over the past couple weeks a that a bunch of premium games have suddenly become free. This isn’t a mistake, nor is it some last hurrah before Apple Arcade hits, and it’s important to know that these games aren’t actually becoming... | Read more »
Yoozoo Games launches Saint Seiya Awaken...
If you’re into your anime, you’ve probably seen or heard of Saint Seiya. Based on a shonen manga by Masami Kurumada, the series was massively popular in the 1980s – especially in its native Japan. Since then, it’s grown into a franchise of all... | Read more »
Five Nights at Freddy's AR: Special...
Five Nights at Freddy's AR: Special Delivery is a terrifying new nightmare from developer Illumix. Last week, FNAF fans were sent into a frenzy by a short teaser for what we now know to be Special Delivery. Those in the comments were quick to... | Read more »
Rush Rally 3's new live events are...
Last week, Rush Rally 3 got updated with live events, and it’s one of the best things to happen to racing games on mobile. Prior to this update, the game already had multiplayer, but live events are more convenient in the sense that it’s somewhat... | Read more »
Why your free-to-play racer sucks
It’s been this way for a while now, but playing Hot Wheels Infinite Loop really highlights a big issue with free-to-play mobile racing games: They suck. It doesn’t matter if you’re trying going for realism, cart racing, or arcade nonsense, they’re... | Read more »
Steam Link Spotlight - The Banner Saga 3
Steam Link Spotlight is a new feature where we take a look at PC games that play exceptionally well using the Steam Link app. Our last entry talked about Terry Cavanaugh’s incredible Dicey Dungeons. Read about how it’s a great mobile experience... | Read more »
PSA: GRIS has some issues
You may or may not have seen that Devolver Digital just released GRIS on the App Store, but we wanted to do a quick public service announcement to say that you might not want to hop on buying it just yet. The puzzle platformer has come to small... | Read more »
Combo Quest (Games)
Combo Quest 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: Combo Quest is an epic, time tap role-playing adventure. In this unique masterpiece, you are a knight on a heroic quest to retrieve... | Read more »
Hero Emblems (Games)
Hero Emblems 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: ** 25% OFF for a limited time to celebrate the release ** ** Note for iPhone 6 user: If it doesn't run fullscreen on your device... | Read more »
Puzzle Blitz (Games)
Puzzle Blitz 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Puzzle Blitz is a frantic puzzle solving race against the clock! Solve as many puzzles as you can, before time runs out! You have... | Read more »

Price Scanner via MacPrices.net

$250 prepaid Visa card with any Apple iPhone,...
Xfinity Mobile will include a free $250 prepaid Visa card with the purchase of any new iPhone, new line activation, and transfer of phone number to Xfinity Mobile. Offer is valid through October 27,... Read more
Sprint is offering the 64GB Apple iPhone 11 P...
Sprint has the new 64GB iPhone 11 Pro available for $12.50 per month for new customers with an eligible trade-in in of iPhone 7 or newer. That’s down from their standard monthly lease of $41.67. The... Read more
Final week: Apple’s 2019 Back to School Promo...
Purchase a new Mac using Apple’s Education discount, and take up to $400 off MSRP. All teachers, students, and staff of any educational institution with a .edu email address qualify for the discount... Read more
Save $30 on Apple’s AirPods at these reseller...
Amazon is offering discounts on new 2019 Apple AirPods ranging up to $30 off MSRP as part of their Labor Day sale. Shipping is free: – AirPods with Charging Case: $144.95 $15 off MSRP – AirPods with... Read more
Preorder your Apple Watch Series 5 today at A...
Amazon has Apple Watch Series 5 GPS models available for preorder and on sale today for $15 off Apple’s MSRP. Shipping is free and starts on September 20th: – 40mm Apple Watch Series 5 GPS: $384.99 $... Read more
21″ iMacs on sale for $100 off Apple’s MSRP,...
B&H Photo has new 21″ Apple iMacs on sale for $100 off MSRP with models available starting at $999. These are the same iMacs offered by Apple in their retail and online stores. Overnight shipping... Read more
2018 4 and 6-Core Mac minis on sale today for...
Apple resellers are offering new 2018 4-Core and 6-Core Mac minis for $100-$150 off MSRP for a limited time. B&H Photo has the new 2018 4-Core and 6-Core Mac minis on sale for up to $150 off... Read more
Save $150-$250 on 10.2″ WiFi + Cellular iPads...
Verizon is offering $150-$250 discounts on Apple’s new 10.2″ WiFi + Cellular iPad with service. Buy the iPad itself and save $150. Save $250 on the purchase of an iPad along with an iPhone. The fine... Read more
Apple continues to offer 13″ 2.3GHz Dual-Core...
Apple has Certified Refurbished 2017 13″ 2.3GHz Dual-Core non-Touch Bar MacBook Pros available starting at $1019. An standard Apple one-year warranty is included with each model, outer cases are new... Read more
Apple restocks 2018 MacBook Airs, Certified R...
Apple has restocked Certified Refurbished 2018 13″ MacBook Airs starting at only $849. Each MacBook features a new outer case, comes with a standard Apple one-year warranty, and is shipped free. The... Read more

Jobs Board

Student Employment (Blue *Apple* Cafe) Spri...
Student Employment (Blue Apple Cafe) Spring 2019 Penn State University Campus/Location: Penn State Brandywine Campus City: Media, PA Date Announced: 12/20/2018 Date Read more
Geek Squad *Apple* Master Consultation Agen...
**732907BR** **Job Title:** Geek Squad Apple Master Consultation Agent **Job Category:** Services/Installation/Repair **Location Number:** 000360-Williston-Store Read more
*Apple* Mobile Master - Best Buy (United Sta...
**728519BR** **Job Title:** Apple Mobile Master **Job Category:** Store Associates **Location Number:** 000853-Jackson-Store **Job Description:** **What does a Best Read more
*Apple* Mobility Pro - Best Buy (United Stat...
**733006BR** **Job Title:** Apple Mobility Pro **Job Category:** Store Associates **Location Number:** 000865-Conroe-Store **Job Description:** At Best Buy, our Read more
*Apple* Mobility Pro-Store 149 - Best Buy (U...
**731985BR** **Job Title:** Apple Mobility Pro-Store 149 **Job Category:** Store Associates **Location Number:** 000149-Towson-Store **Job Description:** At Best Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.