Comment 13 for bug 51000

Interestingly, if I close Firefox, the xrestop numbers drop about what you'd expect (~83 MB):

xrestop - Display: localhost:0
          Monitoring 35 clients. XErrors: 0
          Pixmaps: 30777K total, Other: 841K total, All: 31619K total

res-base Wins GCs Fnts Pxms Misc Pxm mem Other Total PID Identifier
2600000 11 48 1 25 18 9287K 2K 9290K ? Spark - graeme
3400000 5074 36 0 2539 7640 8707K 298K 9006K 6263 notification-d

However, the actual memory usage of X hasn't dropped anywhere near that much:

 4857 root 16 0 203m 146m 12m S 35 7.3 58:52.79 Xorg

And with only 30 MB being used for pixmaps (according to xrestop), there's no explanation for why X is still using 146MB of RAM.

Is there any other way than xrestop to figure out what X's memory is being used for?