Would performance increase with average internet speed (upload), right now it's ~5.34 MBit/s[1] which probably gets worse when hopping through several nodes. It's a shame Ookla doesn't provide latency statistics. I'm sure ping is a big factor too.

Might be interesting to see if a few computers strictly on a LAN could communicate quickly over networks like these or if the actual software is slow.

[1] http://netindex.com/upload/#