16GB 512
I actually still have Sequoia on a partition because I haven’t transferred everything yet, but I’ve not perceived any performance difference when I have switched directly between the two OSes.
Honestly the real performance issue for me is the 16GB max RAM on the M1 model. I have a habit of opening tons of browser tabs across several Safari windows, while also running other things. At some point things start to stutter, until I open Activity Monitor and quit the most offensive tabs hogging the RAM. I’ve continued this habit on Tahoe as well and it’s the exact same experience as on Sequoia, no worse or better.
So for me, with plenty of RAM (like on my 24GB M3 MBA, or on 16GB without anything heavy open) it runs just fine, and with RAM constraints / my over-usage it runs just as bearable-not-great as on Sequoia. I figure this context is useful to our question as I’ve regularly pushed my M1 and am well-acquainted with its performance limits.