In my case, it is not that much CPU usage, as the memory usage. Flyertalk forum pages are extremely heavy. Web browser (and I tested this on FF, Opera, and I believe Chrome, but it's been a while) gets bogged down when you open several pages on FT.
And even when you close them, since FF caches the closed pages for a while (to "reopen recently closed pages", I believe), - the memory usage by the browser remains high. And if you have any other programs open on the same computer, the OS starts swapping the memory to the HDD, and that can bring the OS to crawling. I suspect there might also be some heavy JS in the page source that contributes to the problem.

So, the suggestion to the FT developers is to look into how to make all FT pages lighter: both for memory and CPU usage.