So, a close/reopen of FF puts it down to ~26%. I have about 14 tabs open. I don't feel that my computer is slowing down anyway just surprised at how much it was using when I checked (it is a work one and we have plenty of apps on it that do that) but it just seemed a lot for a browser. As for my Windows Defender to answer the OPs question in task manager it is ~5% that it is consuming. I am lazy at closing tabs so part of it is self-inflicted. Thanks.