OK. Please reduce the problem down to a single app, like just Firefox. Now, please let us know: 1. The version of Firefox; and 2. What web page(s) cause the biggest problem.
I think my list of planned fixes for Ubuntu 18.10  will be the best avenue for helping you because the Celeron 847 has a passmark  of 936, and I estimate gnome-shell presently requires a CPU with passmark around 5000 or more to run smoothly. Obviously we need to get that number down a lot by optimizing gnome-shell in future...  https://trello.com/c/pe5mRmx7  https://www.cpubenchmark.net/cpu_list.php ** Tags added: performance -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to gnome-shell in Ubuntu. https://bugs.launchpad.net/bugs/1773502 Title: High CPU usage To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/1773502/+subscriptions -- desktop-bugs mailing list firstname.lastname@example.org https://lists.ubuntu.com/mailman/listinfo/desktop-bugs