if you are interested in other people helping you: these kind of ”bread crumps”/info bits are not serving that cause. What version of macOS? Mac specs? If Safari is the only program running: what internet connection? Do you use a VPN? What are the
memory requirements of Safari when that happens - how many tabs open?; any Safari extensions?; any adblocker? can you provide the link of an ”example” page which induces
what behaviour exactly? You check with any other browser? You check wether the behaviour persists for a different user? Otherwise: what background programs are running (start up items)? What have YOU done so far to address the problem?
If indeed your computer ”literally” starts ”moving like a snail…” as you write, that’s of course
literally a different kind of problem 😉
Oh, in case you just want to vent… we’ll, o.k.a.y. I guess…