SourceTree is running very, very, slow at times. Restarting it seems to work temporarily, but it's still quite a nuisance, specially when I have to do it every couple of ours. When ST starts slowing down, I also see the CPU usage rising to 80%-300%.
I'm using SourceTree 1.5.7.1 now, but it was also happening with 1.5.7.
This might be the same issue. See my process sample taken with Activity Monitor here.