I'm using ST2 on Debian sid (GNOME desktop) on a Lenovo (X200, Intel gfx, open source drivers) laptop. I've noticed that when an external monitor is plugged & used instead of the laptop screen, ST2 freezes every few seconds, for a second or two. I've managed to reproduce this with 2059, 2051 and 2031 builds. My laptop resolution is 1280x800 (EDIT: corrected resolution), the external monitor one is 1680x1050, and when it's connected, I always use only the external monitor.
I've tried stracing it, but it's pretty noisy and I couldn't find any obvious freezes there. I'm not sure if the freezes are due to some I/O, or something just hogs the CPU (the CPU usage doesn't seem to be too high, so I suspect it's somewhere in IO). The mad thing is, the freezes either happen every few seconds, or they don't happen at all (for hours, or until I close it and open next time perhaps).
One thing I did notice, is that hitting Alt tab *always* unfreezes it (and anything I typed while it was frozen is replayed).
Software versions: X.Org X Server 1.10.1 (2011-04-15), kernel 2.6.38-2-686-bigmem