I've included the jpeg decoder in a recent wp7 project and I'm seeing rough performance. I think the cause is the number of exceptions being thrown.
A first chance exception of type 'System.IO.EndOfStreamException' occurred in ImageTools.IO.Jpeg.dll
A first chance exception of type 'FluxJpeg.Core.IO.JPEGMarkerFoundException' occurred in ImageTools.IO.Jpeg.dll
I see a large number of these when I try to batch process a number of images. I took a brief look at the code and it looks like they are being thrown to control program flow?
ImageTools is awesome btw. Thanks for putting this out there.