I was approached by someone in the IRC channel that said he's going to take a
look at it, and after I said thank you to him and he left, I realized that I was
actually supposed to fix this problem for my colleagues.
So I went ahead and take a look anyway.
The root cause was that the TarOutputStream used in FilePath.copyRecursiveTo()
was flushing buffers too often, and that was causing the unnecessary network
traffic. I also removed the recording of where Command objects are created for
ProxyOutputStream.Chunk to cut the overhead.
This fix will be in 1.311.