Well, after I got home I tried Adobe Fucking Updater again. This time it popped up a dialog saying “no updates to be installed” so quickly I didn’t even notice how much RAM it was taking. Certainly a far cry from hours and gigabytes of memory that it took when I ran it at work.
Also, I did a Time Machine backup for the first time in a few days. I’d started it in the morning, but it was taking too long so I’d aborted it after about half an hour. I started it again when I got home, and expected it to take 5 or 10 minutes like it usually does, or maybe a bit longer because I’d just installed the Leopard 10.5.2 and Graphics updates. Instead it ground and ground and ground and finally finished 3.5 hours after it had started. I’m told this is because the disk was nearly full, and it had to re-arrange old backups to discard the appropriate old ones.