We've made a lot of progress. You'll see people saying that their performance problems have gone away. But we have a long way to go.

Two things to fix: downloading repos is slow (latency, too many small files); and conflict merging can be slow under a few cases. The first one we have a fix for from a summer of code project, but needs more work. The second issue is a very deep, very serious, and will take us a seriously long time to think through.