Is OSX 10.6.8 too old? Constant slow/lockup w/ FireFox, which constantly draws high %CPU rate I switched to FireFox when Safari started to have massive problems.  Firefox is not much better.  Mozilla forum responses keep blaming AddOn incompatability.  But mostly I'm running security &amp; privacy enhancers (DoNotTrackMe, Ghostery, etc)

I have a DSL line.

I've got an MBP 2.66 Ghz Core i7, wish I could install more than 8 GB memory.  I tried a PCI card, but it causes a kernel panic (Delkin Devices ExpressCard 34 PRO SSD PCI Express)

I want to keep >100 tabs open.  Closer to 200.  Used to be able to do that with Safari.  What has changed ?

FF was working adequately until the last security update.  Now its just constantly showing anywhere from 20% to 80+ %CPU usage. It can take many seconds to open a new blank tab, and then 10-20 seconds before it accepts input (trackpad click on the URL box, or keyboard entry).

Seems like every other FF update screws it up.
The problem seems to be that you want to keep 200 tabs open. Try reducing this number and the computer should perform better.