Is interfacer supposed to be slow?

[OscarVanL]

We have noticed that go generate takes awfully long since we started using interfacer. Compared to mockgen, interfacer seems to take several orders of magnitude longer to run per file.

Is this by design/unavoidable or is this a bug?

[rjeczalik]

Is this by design/unavoidable or is this a bug?

There are no optimization in the interfacer at all, like caching loaded packages etc. Definitely it can be improved performance-wise.