Server crash when go into Nether

When a player go to nether with existing portal.

The server lag (1-6 players connected) or crash (6+ players connected)

There are a datapack for disable all IA on mobs (because that crash server, not reported here)

Exemple of log when someone travel with portal (without crash)

19.02 15:55:14 [Server] Server thread/WARN Something's taking too long! 'root.tick.connection.entityBaseTick.portal.placing' took aprox 1647.887406 ms
19.02 15:55:14 [Server] Server thread/WARN Something's taking too long! 'root.tick.connection.entityBaseTick.portal' took aprox 1649.002645 ms
19.02 15:55:14 [Server] Server thread/WARN Something's taking too long! 'root.tick.connection.entityBaseTick' took aprox 1649.111657 ms
19.02 15:55:14 [Server] Server thread/WARN Something's taking too long! 'root.tick.connection' took aprox 1649.403214 ms
19.02 15:55:14 [Server] Server thread/WARN Something's taking too long! 'root.tick' took aprox 1669.647749 ms
19.02 15:55:14 [Server] Server thread/WARN Something's taking too long! 'root' took aprox 1669.692604 ms
19.02 15:55:15 [Server] Server thread/WARN Something's taking too long! 'root.tick.connection.entityBaseTick' took aprox 1386.928802 ms
19.02 15:55:15 [Server] Server thread/WARN Something's taking too long! 'root.tick.connection' took aprox 1387.389372 ms
19.02 15:55:15 [Server] Server thread/WARN Something's taking too long! 'root.tick' took aprox 1412.907496 ms
19.02 15:55:15 [Server] Server thread/WARN Something's taking too long! 'root' took aprox 1412.950275 ms
19.02 15:55:15 [Server] Server thread/WARN Can't keep up! Is the server overloaded? Running 2979ms or 59 ticks behind

Thanks