IMovie 10.0.2 slowed way down exporting movies

Question

it was hitting the system (mac mini, OSX 10.9.1, 8GB RAM, 2.6GHz Intel Core i7) fairly hard and making good progress through the background queue, but now it is only using 4% CPU and hardly making any progress.
it doesn't seem to be hitting the disk either.
is there a log file so i can tell what it's doing in the background?
is there a CPU cap suddenly in place?
how do i tell it to use MORE CPU?
my system is pretty solidly between 95% and 98% idle.
thanks in advance,
jeff

Answer 1

figured out part of it-- the part where it's using no resources and not making progress on the exports: sometimes when i quit out of iMovie and it has to cancel background processes, there's a process that doesn't die like it should. in ps it starts like this:
/Applications/iMovie.app/Contents/PlugIns/Compressor/CompressorKit.bundle/Conten ts/Frameworks/Compressor.framework/Versions/A/Frameworks/StompUtil.framework/Res ources/ProTranscoderTool_sb
if i kill that process, then when i start iMovie up again it uses more CPU (10-20%) and does the exports like it should.
it doesn't seem to be thrashing the disk; pity i can't get it to utilize more of the CPU...
-jeff