I regularly get a problem with Firefox (latest version) where it just keeps me waiting when trying to access sites. I finally found out that by going to Preferences-Advanced-Network and pressing the "Clear now" button in the section named "Cached web content" I can try those sites again and they load just fine. But as I said this is a regular problem. Seems to be happening whenever the cache reaches 350 Mb or so. I'm on OSX 10.6.8 on a Mac Pro 5.1 with an SSD for OSX/my apps and 24 GB of RAM, so I don't see why my hardware should cause any problems.