Clear your browser history of EVERYTHING.
At the top here it says HISTORY. Click and press CLEAR RECENT HISTORY. EVERYTHING. Watch the CPU and wait a couple seconds. CPU should drop significantly.
This will mean you will have to re-login to each website.
Try this for a start.
I forgot to add, after you clear your browser history, close it, wait a few seconds for everything to quiet down, and then restart the browser.
Deleted History. No change.