I am using viaversion, and I have a 1.8.8 spigot server to support all versions from viaversion. But whenever I connect with versions above 1.8 (ex. 1.9,1.10, till 1.14.4) I get lag on join for about 5-10 seconds, also when i TP to a player, or anywhere else. But when join with 1.8 minecraft versions, the server seems to be responding immediately and there is no lag.