Fixed #23745 -- Improved migrate speed

Of course, commit c7ea633 will not be eventually included, it only serves to measure performance.
I thought about that as well. The only question I have is, do we already show it for a verbosity of 2 or only 3? I normally to run everything with `-v 2`, but the elapsed time is nothing that'd be useful unless I'm debugging something, which I would run with `-v 3` anyway.