Dear Mozilla. Yes, I'm using the dreaded Windows 10, I do understand it's at end-of-use, however this prob's been happening for ages. It's just got a little worse lately! (I've also got another hard drive with Windows 7 on it I swap the Windows 10 drive for sometimes. And we don't talk about the Windows XP hard drive with my music software on it. AARRRGGGHHH!!!! But the everyday drive with this problem is definitely Windows ) I don't use masses of extensions, just a VPN (which is there but not used a lot!) and is Proxy VeePN (that's its name, blame the designers, not me!) When I'm NOT using Firefox for a few moments, I hear the fans speed up, the hard drive spins like it's about to take off (old computer here!) The moment I touch the mouse, the fans all slump back to normal and the red 'HIGH USAGE' mark against Firefox vanishes back down to 'LOW'. Which makes it annoyingly difficult to analyze what's happening cos the moment I touch the mouse to find out what's happening, it stops happening! Despite the above and its memory addiction - left to itself it munches memory like me with a crate of chocolate bars! - I do love Firefox best of all the browsers. I kinda know what causes the memory problem, by the way. I don't know all the techie terms but here's what's going on. Imagine you've got a house with an untidy kid in it. Every time one room gets too messy to use, you move into the next room. Eventually you run out of rooms. Then you restart the house back from day one, all the rooms are tidy again and you can use them all individually and happily - until Untidy Kid turns back up! I'm on Firefox 148.0.2. If you've got any ideas about the CPU usage, I'm ''[email removed]''@hotmail.com. It doesn't seem to matter what websites I've got in the browser, it just does this when I've got it parked in the background, it's like it's twiddling virtual thumbs through boredom cos it's not being used. Yours respectfully, Chris.