I suppose misery loves company: I'm so relieved to find I'm not the only one. Using microcore 2.10 with Xorg-7.4 and beaver2 from the 2.x repo. A little editing on a large-ish file will stall the system for ages (or permanently). If I use IceWM, its little system usage meter on the taskbar fills right up and stays that way.
After reading these posts I experimented a little, and found that certain GTK 2 engines make the problem worse, especially Murrine. GTK themes using older, simpler engines like Pixmap, Industrial, or Glide produce a smaller problem, and with a little patience and much pausing, it catches up to itself.
As a side note, with a fellow mini-Linux distro (SliTaz 3.0) on this very same hardware with the same version of Beaver, there's no problem.