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

Pinegrow Web Designer 2.94 - Mockup and...
Pinegrow Web Designer is desktop app that lets you mockup and design webpages faster with multi-page editing, CSS and LESS styling, and smart components for Bootstrap, Foundation, Angular JS, and... Read more
ExpanDrive 5.4.1 - Access cloud storage...
ExpanDrive builds cloud storage in every application, acts just like a USB drive plugged into your Mac. With ExpanDrive, you can securely access any remote file server directly from the Finder or... Read more
MacUpdate Desktop 6.1.3 - Search and ins...
MacUpdate Desktop 6 brings seamless 1-click app installs and version updates to your Mac. With a free MacUpdate account and MacUpdate Desktop 6, Mac users can now install almost any Mac app on... Read more
VOX 2.8.6 - Music player that supports m...
VOX just sounds better! The beauty is in its simplicity, yet behind the minimal exterior lies a powerful music player with a ton of features and support for all audio formats you should ever need.... Read more
Espionage 3.6.6 - Simple, state-of-the-a...
Espionage offers state-of-the-art encryption and plausible deniability for your confidential data. Sometimes, encrypting your data isn't enough to protect it. That's why Espionage 3 goes beyond data... Read more
VOX 2.8.6 - Music player that supports m...
VOX just sounds better! The beauty is in its simplicity, yet behind the minimal exterior lies a powerful music player with a ton of features and support for all audio formats you should ever need.... Read more
MacUpdate Desktop 6.1.3 - Search and ins...
MacUpdate Desktop 6 brings seamless 1-click app installs and version updates to your Mac. With a free MacUpdate account and MacUpdate Desktop 6, Mac users can now install almost any Mac app on... Read more
ExpanDrive 5.4.1 - Access cloud storage...
ExpanDrive builds cloud storage in every application, acts just like a USB drive plugged into your Mac. With ExpanDrive, you can securely access any remote file server directly from the Finder or... Read more
Espionage 3.6.6 - Simple, state-of-the-a...
Espionage offers state-of-the-art encryption and plausible deniability for your confidential data. Sometimes, encrypting your data isn't enough to protect it. That's why Espionage 3 goes beyond data... Read more
Pinegrow Web Designer 2.94 - Mockup and...
Pinegrow Web Designer is desktop app that lets you mockup and design webpages faster with multi-page editing, CSS and LESS styling, and smart components for Bootstrap, Foundation, Angular JS, and... Read more

HeadlessD (Games)
HeadlessD 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: HeadlessD is hand-painted dungeon crawler with intuitive touch controls and NO in-app purchases. | Read more »
Leaf for Twitter (Social Networking)
Leaf for Twitter 1.0.1 Device: iOS iPhone Category: Social Networking Price: $4.99, Version: 1.0.1 (iTunes) Description: | Read more »
Banner Saga 2 (Games)
Banner Saga 2 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: The epic award winning story-based role-playing game continues its emotional journey across a breaking world. Lead your Viking... | Read more »
Concrete Jungle (Games)
Concrete Jungle 1.16 Device: iOS Universal Category: Games Price: $4.99, Version: 1.16 (iTunes) Description: A follow up to the puzzle hit 'MegaCity'! Concrete Jungle is a new take on the city building genre that swaps micro-... | Read more »
5 great apps for the budget traveller
Travelling abroad, or even within your home country, has never been easier thanks to our handy smartphone companions. There are hundreds of apps on the market that promise to make your world journeys hassle-free, but we've selected five of the... | Read more »
Zip—Zap (Games)
Zip—Zap 1.01 Device: iOS Universal Category: Games Price: $1.99, Version: 1.01 (iTunes) Description: Touch to contract.Release to let go.Bring the clumsy mechanical beings home. · · · over 100 levelsno adsno in-app-purchases Zip—... | Read more »
Paperback: The Game (Games)
Paperback: The Game 1.0 Device: iOS Universal Category: Games Price: $3.99, Version: 1.0 (iTunes) Description: You are an author trying to finish kitschy paperback novels. Complete Westerns, Science Fiction, Romance or even a Crime... | Read more »
How to Rule With a Firm Hand in My Majes...
My Majesty is a kingdom management sim not unlike August’s magisterial hit, Reigns. It’s essentially a reskin of developer Tigrido’s previous management sim, Dictator. As supreme ruler of the land, you must consult with a number of subjects to... | Read more »
Our 5 Favorite iMessage Sticker Packs
At long last, iMessage joins the ranks of messaging apps the likes of LINE and Whatsapp, adding an impressive collection of stickers. They’re a great way to add a little something extra to your daily conversations. [Read more] | Read more »
How to get past Vulture Island's tr...
Vulture Island is a colorful and quirky mish-mash of platforming and puzzles. It’s creative and fresh, but sometimes the game can throw a curveball at you, leaving you stuck as to how you should progress. These tips will help you explore smoothly... | Read more »

Price Scanner via MacPrices.net

Apple refurbished Mac minis available startin...
Apple has Certified Refurbished Mac minis available starting at $419. Apple’s one-year warranty is included with each mini, and shipping is free: - 1.4GHz Mac mini: $419 $80 off MSRP - 2.6GHz Mac... Read more
13-inch 2.5GHz MacBook Pro available for $928...
Overstock has the 13″ 2.5GHz MacBook Pro available for $927.99 including free shipping. Their price is $171 off MSRP. Read more
Buying McLaren Would Give Apple Instant Car C...
Apple “iCar” rumors have waxed and waned over the years, piquing interest and speculation as to whether Apple is seriously interested in getting into the automotobile business, either in a joint... Read more
Aetna to Transform Members’ Consumer Health E...
Health care benefits company Aetna, which has an estimated 46.3 million clients, today announced a new initiative to revolutionize members consumer health experience by combining the power of iOS... Read more
USB-IF Announces USB Audio Device Class 3.0 S...
USB Implementers Forum (USB-IF), the support organization for the advancement and adoption of USB technology, today announced the USB Audio Device Class 3.0 specification to establish USB Audio over... Read more
Clearance 12-inch 1.2GHz Retina MacBooks, App...
Apple has Certified Refurbished 2015 12″ 1.2GHz Retina MacBooks available for $1189, or $410 off original MSRP. Apple will include a standard one-year warranty with each MacBook, and shipping is free... Read more
Logitech SmartDock and Skype For Business Com...
Logitech has announced Logitech SmartDock, an AV meeting room solution designed in collaboration with Microsoft. Logitech SmartDock works with Skype for Business and qualified devices, including... Read more
27-inch iMacs on sale for up to $220 off MSRP
B&H Photo has 27″ Apple iMacs on sale for up to $200 off MSRP including free shipping plus NY sales tax only: - 27″ 3.3GHz iMac 5K: $2099 $200 off MSRP - 27″ 3.2GHz/1TB Fusion iMac 5K: $1899.99 $... Read more
Apple Macs and iPads available for up to $300...
Purchase a new Mac or iPad using Apple’s Education Store and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free, and... Read more
Save up to $600 with Apple refurbished Mac Pr...
Apple has Certified Refurbished Mac Pros available for up to $600 off the cost of new models. An Apple one-year warranty is included with each Mac Pro, and shipping is free. The following... Read more

Jobs Board

*Apple* Retail - Multiple Positions- Chicago...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* Retail - Multiple Positions- Raleigh...
Job Description:SalesSpecialist - Retail Customer Service and SalesTransform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
User Support Specialist *Apple* Product Spe...
…Description:Ciber, Inc. is seeking a User Support Specialist - Apple Product Support in Nashville, TN!Responsibilities:Support, implementation, and upgrade of Read more
Restaurant Manager (Neighborhood Captain) - A...
…in every aspect of daily operation. WHY YOU'LL LIKE IT: You'll be the Big Apple . You'll solve problems. You'll get to show your ability to handle the stress and Read more
US- *Apple* Store Leader Program - Apple (Un...
…Summary Learn and grow as you explore the art of leadership at the Apple Store. You'll master our retail business inside and out through training, hands-on Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.