Time Machine backing up way too many files

A little while ago I noticed Time Machine was taking forever to perform its hourly backups on my work computer (MacBook Pro, 10.6.8). I downloaded TimeTracker and Time Machine Buddy, and compared TM's performance between my work and home Macs. Let me lay out my observations and the problem for you:

- Regular backups routinely take 20-30 minutes on the work computer; sometimes longer; they usually take about 1 minute at home.

- My wife works at home so both Macs are used about the same amount during the day.

- According to TimeTracker, these normal backups basically have the same makeup on both Macs. Around 40-60 MBs of data, and the biggest single file tends to be something in a web browser "Application Support" folder, e.g. Firefox's places.sqlite file at 40 megs.

- When I noticed this, I even excluded that browser file from TM. Didn't have an effect.

- The biggest difference between the two Macs that I can glean from Time Machine Buddy is the sheer number of files being prepared and copied. At home, it's a few thousand, maybe 3-4. At work, more like 100,000. In fact, all of my overnight backups were identical: 60,744 files copied (14 KB) followed by 28,176 files copied (9 KB). So, it's clearly not linked to the size (data-wise) of the backup. (Again, this was less data after I excluded that FF folder. I've since re-instated it.)

- I don't see anything in the TM Buddy log about a "deep traversal."

- Can't imagine it's an external HDD issue since (I assume) all the TM preparations should be happening on the Mac side, but for what it's worth, this started with one drive (USB 2.0) that I then restored to a larger partition of another drive (FW 800), and the issue persists.

I've seen lots of other threads about endless TM backups and regularly copying mountains of data, but hadn't come across anything that seemed to match my peculiar situation.

Thanks for your help!