If use any type of mount (minecart, horse...) and ride it to fast, i get a freeze ingame. My friend also get this freeze (the chunks wont load in front of you and you cant leave the mount but can use buttons like F3 and can look around). Sometimes the server gives out something like this :
" player is sending move packets too frequently (6 packets since last tick)".
I hope I helped and excuse me for my bad english.