My experience with Google Docs makes me want to strangle it. It's slow, unresponsive, uses a ton of memory, and I can't shake the constant nagging weight of surveillance being done against me.

EDIT: Oh, and just this last week, I found it couldn't understand that I wanted to use "set up" as a verb, instead of "setup", the noun. Constant underlining when underlining was neither necessary nor desired. Apparently when I told Docs a month ago to avoid critiquing my grammar (via its Settings), it took my mandate as merely an ephemeral suggestion.

My daily journal is up to 110 pages long. I haven't noticed any performance issues (though it does take 5-6 seconds to load on mobile).

As for autocorrect - you can turn that off in Tools->Spelling and Grammar.

In my experience input lag in Google Docs is very small but noticeable compared to local writing.

You can get used to it, but I prefer more snappy experience.