Network/server is the bottleneck and we don't want to have dozens of requests per second from one user.

I won't say it should be re-opened, but for people running the lib against their own server on localhost (or local network), network/server might not be the bottleneck, and they'd only be server one (or at most a few) user(s).

Either way, that likely won't be implemented in pymb2 anymore. That should be reported to pymbngs.

However, that would probably be quite some work to be done. (multi threading, possibly also asynchronous requests).
And I personally wouldn't want to forward a 3-year old anonymous ticket to pymbngs (since no current user of pymbngs might actually have this problem)

(pymbngs = python-musicbrainz-ngs)

Trac:

Component: python-musicbrainz2
Version: Picard 0.12.1

This could even be meant for picard.

Just in case somebody with this problem is reading this:

Please report the issue to the actual tool you are currently using.