Safari 3.x suddenly acting bizarre

I have Tiger on a g4, and until yesterday, Safari 3.x was running fine.
Tonight, it keeps hanging up. I fired up activity monitor, and I find
it is eating all the cpu time available and not doing anything. I have
to force quit and relaunch. Twice it hung when I hit quit. Most of the
time, activity monitor calls it active, but the most recent hang-up, it
went red with "not responding." I haven't added anything to the system,
no plug-ins, no new apps save for a Big Fish Games game in a while, so I
am at a lost for what might be happening.

Any thoughts or suggestions?