Comment by mat_b
I have a 4 year old M1 macbook pro running macos 12. It runs as good as when it was new. So you honestly think that if I upgrade it to macos 26 it wont start lagging? I am extremely confident that it will. Even without changing the other software running on it.
Probably for a day or two as various indexes and caches are rebuilt in the background, and then not.
I use 26.x on an "original" 8GB M1 MacBook Air and it's as fine as it ever was.
(I also have a MBP, various Mac Mini's and other desktops, so it's not that I'm just used to everything being slow).