Blockland doesn't seem to like the higher packet rate on many servers. It'll look like this:

I can imagine two causes for this:
1) Too many packets at once, the server doesn't have enough upload to send all of them so many get lost. It takes a long time to re-send them, only to have most of them lost again. Could be fixed by lowering packet rate if over 10% are dropped.
2) Packets arrive unordered and get dropped.
Still getting stuck downloads after this update seems to be related to this. On servers with high packet loss (like above) the download will often freeze for multiple seconds while the client is waiting for the correct packet. It doesn't actually break, if you wait 10-20 seconds it will continue.