I had the same problem last year, re-indexing all the files fixed it for me[1].

That being said, macOS was definitely more snappy back on Catalina, which was the first version I had so I can't vouch for Snow Leopard. Each update after Catalina felt gradually worse and from what i heard Tahoe feels like the last nail in the coffin.

I hope the UX team will deliver a more polished, expressive and minimal design next time.

[1] - https://support.apple.com/en-us/102321

Catalina and Mojave were the closest releases in terms of quality that we got to Snow Leopard. Catalina in particular since it was the release that removed more 32-bit cruft (like Snow Leopard before it).