Issues with integrated server.

It randomly hangs while client keeps running. Easy way to spot it blocks stop dropping. This can last for several seconds to minutes.

Its so bad integrated server hangs on every save world event and closing game with world saving can take more then 5 minutes to resume activity.

Could not test with external server if issue happens there too, my Linux server has not fresh enough openjavadk to run it available.

On that note, 1.16.5 with several mods and 1.17.1 runs just fine.