From snapshot 24w14a to the latest prerelease, I occasionally get a lag spike about every 30 seconds or so. This doesn't happen in 24w13a or earlier. I suspect that it may be caused by java's garbage collection, as when the lag spike happens, the memory usage goes down in the top-right of the debug screen. It doesn't always happen when the memory usage goes down, it only happens around half the time.

The only significant thing that is different between 24w13a and 24w14a is the change from Java 17 to 21, so something about java 21 could be causing the issue.