Hello, I use FireFox (FF) Ver. 53.0.3 (32 bit) on a Windows 7 Premium PC (additional details in attached image). I also use Tab Groups 1.0.2 and have used this arrangement for a very long time (FF updates excepted). I also have a desktop CPU usage 'gadget'. When FF introduced Tab Groups (Panorama if I recall) many years ago I began using it immediately. At that time I was able to open many tabs (20-30 before my RAM became overloaded (if I understand what was happening) and would then have to switch to the tabs screen, collapse the group in use, open a new blank tab, expand it and then close FF to allow the RAM to return to a normal level; at which time I could begin again (with the prior tabs in the reduced group being 'dead', don't know how else to describe it) opening to a new blank FF screen and begin again. This became 'normal' for me and was the situation up until the last 6-12 months and allowed me to collect several hundreds of tabs relatively efficiently. If I delayed this process and opened too many tabs FF would crash, but I was able to recover the prior work when FF restarted in most every event (I'll call this the 'process' hereafter). When FF discontinued 'Panorama' I switched to the Tab Groups program noted above and nothing changed. Beginning about a year ago, I began noticing that I was unable to open as many tabs at one time as I had been used to before the demand slowed the computer and I had to go through the process described above. Because of this I began monitoring the Processes tab in my task manager and noticed that 'Memory (private working set)' for FF was running at ~ 1 X10^6 at the time FF would begin slowing seriously and I would need to repeat the process described above, but I was still able to have 15-20 tabs open at a time. Recently, however, the number of tabs I'm able to have open is even lower (sometimes as low as 6 but usually 10-15) causing me to have to repeat the 'process' more & more frequently. FF rarely crashes when I 'overload' the system now, but when the 'memory' usage gets >> 10^6 I find that when I close FF (using the 'X' at the upper right of the screen) FF doesn't actually close (see images of CPU meter & Task Mgr) and even though FF is not listed as a running process in the Task Mgr 'Applications' window, it is still running as seen in the 'Processes' window. When this happens, I use the 'End Process Tree' in the FF left click drop-down window, which closes FF. After doing this, and the RAM winds down to a normal level (35-40% per my CPU monitor) I restart FF which usually starts & runs normally. Sometimes, however, it appears to start normally, but when I go to tabs view and then try to return to screen view, there's brief flicker (like a screen reset) and it stays in tabs view and will not go to screen view. I must again, go to the task mgr to shut FF down as above. FF will then usually run normally, but if the same thing happens again (twice in a row) and I restart FF It starts normally but opens the "Well, this is embarrassing…" window and I have to have FF reload the prior work. I realize this is long & possibly confusing. I'll be happy to clarify what I can. The 1st image is my computer specifications from CCleaner's pgae. The 2nd image is a composite of the issue showing, on the right, my CPU monitor with RAM at 79% useage. In the middle is the Task Mgr showing FF use at > 3 billion (whatevers), and on the lower left is an arrow showing my FF icon not highlighted (i.e.; FF is showing as 'off'). Can someone tell me what's going on here and how to get back to a more efficient way of working? Thanks.