Performance tip - $root.$prefs.$maxCacheClasses

Doug Easterbrook doug at
Sun Dec 21 23:06:31 EST 2014

hi all:

I was playing around with our Omnis Studio library on the weekend - which has some 3000+ classes in it.   It performs really well, but I hit a small snag trying to make it perform well under the scenario where the library was not on the same drive as the application…   There is a reason that I want the library on a server (macintish - network user situation)

performance went down - dismally.

and then I discovered my saviour — a preference that can be set at run time.


initally it was set to 300 (as it has been for years)…. and so I set it up at 5000 - just for giggles.      After the initial load of my library by the omnis runtime, I got a bunch of performance back because more of the classes are being stored in ram.

so if you are not aware of this setting — its worth knowing.

you can also look at
sys(190) - to see the number of classes loaded by the runtime and
sys(191) - to see the number of classes discarded out of cache

its really a lot faster if your app is not discarding classes out of the cache because $root.$prefs.$maxCacheClasses is set too low.

thats my learning for the weekend.   hope it helps somebody.

Doug Easterbrook
Arts Management Systems Ltd.
mailto:doug at
Phone (403) 536-1205    Fax (403) 536-1210

More information about the omnisdev-en mailing list