It seems to be just the Comcast / XFINITY web pages when checking email using Firefox. Performance is poor, the email page does not keep up with my typing which is not very fast. Putting Firefox in <safe> mode takes care of the performance and the constant, what I believe is the slowing down your browser flickering message that occurs. When going through the stopping of hardware acceleration, Theme, extensions......etc, I could not narrow it down to which area is causing the problem. I have done the <tune up Firefox> and it didn't help. I don't have these same issues when using IE. Obviously my preference is to use Firefox. Note: There is a HP printer extension that Firefox does not recognize and has automatically disabled. Are there any recommended plugins / add ons for Comcast.net (XFINITY) site? I spoke with Comcast support and they said it was a FireFox issue, because it works with IE. I did see a similar question with Charter web email issues. Any suggestions to help narrow the issue down would be appreciated.