Several of the anecdotes on the reddit thread don't even seem to take account what version the offending slowness was happening in, and anecdotally every time I've helped a Windows user experiencing slowness enough to complain about it, they've been years behind on their git version and installing the latest removed the complaints.
[1] ...and is just about guaranteed to in the many places in git where a command is still built as a tower of bash scripts calling perl scripts calling more bash scripts... If you read the changelogs, a lot of the performance optimizations that are helping every platform are the places where entire commands are getting replaced with C versions of themselves.