Hmm, I seem to have the exact same problem… The MaterialEditor is slowed down horribly by this recompile-thing - it’s basically impossible to work with it. It takes like 40 seconds just to recompile the material if I create a blank material with just a simple color in the BaseColor-Channel.
OK, my hardware is not the best (AMD Phenom, 4x2.2 GHz, 4 GB RAM, HD6770) but the whole UDK is running surprisingly well and - guys, honestly - compiling a material with a simple color in the diffuse channel should not take that long??? In UDK3 muuuuch more complex materials could be done easily on my system…?
Is there a fix coming for this? This must be some sort of bug…?