I am glad to see speed search make a return, but at the moment it is more sluggish than with v3 or v1 for Mac.
When doing a speed search, one thing that I think slows things down, or at least gets in the way, is the completion or suggestion menu that automatically drops down. For a standard search this can be nice, for a speed search it gets in the way and I suspect is causing the sluggishness I am seeing with speed search.
I would imagine most people (myself, for sure) doing a speed search would not really need that suggestion menu.