I've just gone through a couple of weeks hassling with one of my blogs. Had lots of problems with publishing timing out. Got to the point where I had to save a post first, then pull it back up and publish it. My blog's back end also seemed pretty sluggish. Finally Bec suggested that I try deactivating plugins one at a time and doing some tests.

I deactivated my Google sitemap plugin and BINGO, no more problems. Just wanted to pass it along.

Michael