I do have the same problem on one of my systems : P4, 2.4Ghz (Hyperthreading), 1024 Mo RAM.
Maybe something related to the Hyperthreading capabiliites of the processor? I think I remember 0.13 version running fine.
I've been running the SVN version for a while now and I've had some serious performance issues as well. The real bugbear right now is updating metadata. That seems to take the longest, though I do sometimes see lagging when I skip a track.
I'll try rebuilding my config directory tonight and seeing if that helps. I'd hate to have to restart it, I've finally got ratings on my entire library. :(
I'm using sqlite-3.5.6