Hey there, did you or any other opped player change the randomTickSpeed or /give someone a lot of items? If they changed the randomTickSpeed start the server but don't join and spam "/gamerule randomTickSpeed 3" in console (CaSe sensitive). If they spawned in a bunch of items start the server, don't join, and spam "/minecraft:kill @e[type=minecraft:item]" in your console. (type command HERE)