The parkour server has a major problem that can be seen as an advantage in some situations and a nuisance in others: lagback.
This does not happen in other servers like creative. See, every once in a while, more often than it should be, you jump or fall off of a block and it just teleports you back. Sometimes, you make it onto the next block and you're teleported back a few. Other times, you fall off of the block and you're teleported back up for another chance.
I recommend somebody tries to locate the mismatch between the server and the client. What I think the problem is is the server and client arguing where the player is at the moment, similar to the ghost blocks issue on some servers. The player jumps, and either the server or the client thinks that the player did not jump because it is lagging behind what is happening at the moment, causing the player to be teleported back to the last point in which the server and the client were aligned.
This does not happen in other servers like creative. See, every once in a while, more often than it should be, you jump or fall off of a block and it just teleports you back. Sometimes, you make it onto the next block and you're teleported back a few. Other times, you fall off of the block and you're teleported back up for another chance.
I recommend somebody tries to locate the mismatch between the server and the client. What I think the problem is is the server and client arguing where the player is at the moment, similar to the ghost blocks issue on some servers. The player jumps, and either the server or the client thinks that the player did not jump because it is lagging behind what is happening at the moment, causing the player to be teleported back to the last point in which the server and the client were aligned.