i really have no idea how to explain this.. so basically i go on this server: play.mcsn.us and go to kitpvp.. so i have to run around and spring and jump and all that.. so when i get people hitting me and im sprinting the game puts me on one block and untill i stop moving it keeps pulling me back.. so i have to stop mid battle or running.. just so i can move.. and its really annoying..
Two issues it sounds like here, neither which are a problem with the default Minecraft.
To start with this would have to be replicated on an unmodded server, modded servers are not supported here.
Second it sounds like server lag, again you would have to take it up with the admin not here.