There’s a multitude of settings that can be tweaked to improve the indexing time, although not directly related to indexing itself.
Tweaking the Java VM settings in WS is necessary if the project is very large.
Then reduce the number of plugins in use. The default install is a jungle! I discovered with time that I don’t need about 80% of them.
This was the single most important change. It has dramatically reduced the indexing time. It used to be a problem even on a machine with 8th Gen Core i7 + 32GB RAM.
Edit: I’m not entirely sure I should call it “reducing the indexing time”. But it was always about that horrible sluggishness at startup, then at times when you’d refactor file names and such. So I’m thinking it was the indexing process.