10.6: Avoid slow and CPU-intensive Time Machine backups

On my Mac, Time Machine backups sometimes slow to a crawl, and stay like that for hours on end. After some digging, I discovered that Finder is often the culprit, and quitting Finder seems not to have any adverse impact on the backup -- but it does speed it up by an order of magnitude. Here's what happened in my case...

I had been making an initial Time Machine backup over a network. Initial write speeds were over 5mbps, but an hour later, it was down to 100kbps -- and CPU usage went up to almost 90%. I left it this way for four hours and there was no improvement -- at this rate, the backup would take a week.

A look at Activity Monitor showed almost all the CPU usage due to Finder, and a look at the 'Open Files and Ports' by Finder showed it accessing the Applications folder in the backup, crawling through all the application packages over a...