Again, just as a reference, the fetch code gives the firehose; every time a packet is received, off goes a callback. My opinion is that [the documentation should mention](https://github.com/libgit2/libgit2/blob/development/include/git2/clone.h#L38-L40) that this is a potential perf risk, but that callbacks themselves aren't that expensive (nanoseconds) on the scale of network operations (milliseconds).