When I watch a YouTube video with Firefox -- whether I'm watching it in Flash or HTML 5 -- it often stutters. This stuttering problem never happens when I watch the exact same YouTube videos in Chrome or Safari. Here are seven facts about my situation: 1) I am currently using Firefox 5, but this problem has existed for me in Firefox 4 and Firefox 3.6 to the same extent. 2) I always use the latest version of Flash as soon as it's released, and prior to installing the latest version of Flash, always I use the Flash uninstaller to uninstall the previous version. 3) I have a faster than average cable modem Internet connection. A few minutes ago, Speedtest.net said my download speed is 32 Mbps and my upload speed is 6 Mbps. 4) I am using a dual-core Penryn MacBook 2.13 with 4 GB of Crucial-brand RAM, 500 GB Western Digital hard drive with half of it being empty. 5) The YouTube stuttering problem happens even if Firefox is the one and only application open. 6) I recently did a clean install with an OS 10.6.3 DVD, and used the Combo Update to bring it to 10.6.7. I only use Combo Updates for OS X updates, and use Software Update to install all other available updates. 7) I run Disk Utility's "Repair Disk Permissions" at least once a week. Please help. Are any of you reading this having or not having this problem? If you have experienced this problem, is possible to fix it? Thanks for any feedback.