After using Yahoo Mail for an hour or so my memory usage increases to a very high level. Just now, after reading and deleting about 50 e-mails (newsletters etc.) I noticed Firefox 17 running slowly and checked the memory usage in Windows Task Manager (I am using XP) and it was 1.2 Gb. My older laptop only has 2 Gb of RAM. Yahoo Mail was the only thing open at the time. I never notice this problem with Gmail which I mainly use. However I use Yahoo Mail for quite a few newsletters etc. that are less important and which I only check once a week or so. I found the following bug report about 3 years old which almost exactly describes my problem. https://bugzilla.mozilla.org/show_bug.cgi?id=506771 But this report involves a much earlier Firefox version, and at the end it seems to say that the problem was fixed. However it well describes my current issue with Firefox 17, especially the continual increase in memory while using the up/down arrow keys to scroll through Yahoo e-mails. Is this normal to have to shut down and reopen Firefox every hour or so to clean out the memory? For some reason I only notice this when using Yahoo Mail. After using many other sites and having multiple tabs open for several hours I rarely reach that kind of memory usage. About the highest I've seen with other sites after a couple of hours is 600 Kb which is roughly when I start notice slower response times.