When Thunderbird Uses Too Much Memory

So I run Thunderbird on Linux, and the other day at work I noticed thunderbird taking up way too much memory—both virtual and physical, as top(1) showed:

top - 10:57:52 up  2:48,  2 users,  load average: 0.09, 0.08, 0.04
Tasks: 117 total,   2 running, 115 sleeping,   0 stopped,   0 zombie
Cpu(s): 14.3%us,  2.5%sy,  0.0%ni, 83.3%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:    998152k total,   827696k used,   170456k free,    14308k buffers
Swap:  4192252k total,    11084k used,  4181168k free,   398176k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
 4144 collin    20   0  760m 218m  32m R   23 22.5   7:31.57 firefox
 4097 collin    20   0  502m 185m  28m S    0 19.0   4:47.57 thunderbird
 1888 root      20   0 55352  17m 3960 S    8  1.8   2:11.66 Xorg
 4905 collin    20   0 38620  12m  10m S    0  1.2   0:00.88 notification-da
…

The above is from mh home computer, but at work thunderbird was showing something like 1680m virtual size, and the %MEM was something like 70.0. Way, way too high. Of course, it also made the computer run slower than molasses in January.

A web search led me to "Daifne"’s advice on http://forums.mozillazine.org/viewtopic.php?f=39&t=530263#p2794923—the short version of which is to

• quit Thunderbird (probably kill(1) it to be sure), then
• cd into the profile directory and
• remove all files matching *.msf; then
• restart thunderbird and
• compact all folders (this last is optional if you've already got tbird configured to automagically compact folders frequently)

After doing all that, the memory numbers dropped dramatically, to about 1/3 their former values.

Amazing, really, how much easier some things are with the web. Of course the web is partly the cause of so much complexity. Is that dialectical?