I “live in Emacs”, like most of us (atleast at work). It has been getting slower release on release, async support doesn’t seem to have been picked up by most packages and native-comp has made it more brittle.
Over this time, we moved from running the OS on hardware to running in VMs, so fractional slowdown was expected. But what I have is a few X slower Emacs. I had never seen Emacs take a minute to indent a few thousand lines, for example. Maybe some modes have slower code.
Time to reindent lines is something that tends to increase, as indentation quality is improved over the years (and as the need increases to support ever more syntactic features of the indented language).
But it really depends more on the text being indented and the mode in use than on the version of Emacs, IME.
Thanks. True, verilog-mode is maybe 6 times slower than c+±mode. I should add some treesitter grammars and try c+±ts-mode etc.
File opening being slow must be a different aspect.