Server Thread Warnings-Something's taking too long 'root.tick...'

Whenever the 19w09a server is started with debug, Server Thread/WARN messages appear constantly, causing lag at times on the server. Allocating any more RAM does not help, and there are no other processes that are running besides this single server. The main messages that occur are: 'root.tick', 'root.tick.save', 'root.tick.connection', and 'root'.