By watching the Windows XP Task Manager's "Mem Usage" statistic, a possible memory leak in FO's client becomes apparent. I'm not sure how accurate this is, or (see below) how it's dealing with disk caching, but regardless, there seems to be a steady increase in memory usage while just looking at the galaxy map, doing nothing else.
On the main splash screen, doing nothing, Mem Usage is stable at 37484 K. In this test, music is off and sound is on, though sounds being heard (due to button rollovers) seem to have no effect on Mem Usage.
Single player game started - sit looking at map. Starting around 40000 K, increasing ~100 K / s
Time - Mem Usage
4:55 - 50000 K
4:58 - 60000 K
5:04 - 85000 K
5:08 - 100000 K
Then, I minimized the FO window, and Mem Usage dropped to 3452 K, then immediately started growing again ~100 KB / s (while still minimized). Since (after restoring later) FO doesn't seem to have to reload all art, I assume some odd caching is going on here. For the purposes of this bug, I assume this doesn't matter.
Restoring the FO window causes no significant change that can be readily distinguished from the 100 K / s growth, compared to what it was immediately before restoring (ie. growth over time above 3400 K )
Reminimizing returns Mem Usage to ~3400 K