The AMD Warranty Info Page on AMD Community (these forums) causes a massive memory leak, at least in Firefox 80.0.1.
I clicked on your link and then open Task Manager but my results were not as severe as yours but bad enough:
Try disabling your Extensions and see if one of them is causing your huge spike in Memory usage or run FireFox in Safe Mode temporarily and see if it shows the same results.
Same version of FF as the one you have.
I am running 80.0.1 (64-bit) on Windows 10 64bit Pro 19.09 with latest patches - no problem. 791.5MB.
Seems to work fine on Chrome Canary Version 87.0.4257.0 (Official Build) canary (64-bit)
Maybe a 32-bit thing.
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