Text drawing is taking a lot on iPad using iOS 4.2 gm seed

I wrote an app which draws some text on the view using my own custom fonts, and the drawing takes about 200 ms on iPad with iOS 3.2, but after I installed iOS 4.2 BETA a month ago, it took more than 2 to 3 seconds to draw (10 - 15 times more), at that time I thought it's a BETA problem so I rolled back to iOS 3.2, then yesterday I installe开发者_开发知识库d the 4.2 GM Seed (which is considered as a final release) and the same problem happened,

Does anyone have an idea of what's going on?

Thank you for your help and good luck

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Your best bet is to use the Sampler tool in Instruments.app (/Developer/Applications/Instruments.app) to determine where your time is being spent. Then you'll know what is actually slow, and you can optimize what you need to.