LensEffectPanel causes PresentationFontCache to bog down

Question

I've written a WrapPanel that does a lens effect on the controls as you move the mouse over. You can see it in action here:

http://150.101.100.238/~john/LensUniformWrapPanelTester/Swordfish.WinFX.LensTesterWeb.xbap

and download the source here:

http://150.101.100.238/~john/LensUniformWrapPanelTester/Swordfish.WinFX.LensTesterWeb.zip

I have the problem that when running it in debug over and over it gets slower and slower. I've traced the problem down to PresentationFontCache.exe, and if I kill this process before running again my app returns to full speed.  I'm wondering what I can do to avoid this problem.

I noticed that having too many different scale transforms applied in a sequence caused a problem, so I've reduced the number of possible transforms by round my scaled rectangle to the nearest pixel like this:

ScaleTransform transform = new ScaleTransform(Math.Round(theRect.Width)/Math.Round(renderedSize.Width), Math.Round(theRect.Height)/Math.Round(renderedSize.Height));

I'm wondering if maybe there is a way of cleaning out the font cache when I first run my app?

Answer 1

I've realised that my Athlon 64 4800+ dual core is a really fast machine. I've tried running this panel on other machines and it runs slowly on the first run.

On my Athlon though, it initially appears to be running at a smooth frame rate.

Answer 2

I'm starting to think that on a really fast machine PresentationFontCache slows things down in general. I've got a X-Y chart control with zoom and pan, and I notice that ending the PresentationFontCache process while it's running subjectively makes the panning and zooming smoother.

Answer 3

This problem seems to have gone away with the June 2006 CTP