I don't know why; however, I would get these crazy spikes once in a while (not fps drops) but server lags. I have the spark link here
To see if you can help me find what's wrong?
https://spark.lucko.me/XwUZRQSFOn

a) The version of Spark you're using is outdated according to the Spark profile itself.

b) I literally have no idea what's going on with your profile. You appear to be using MCMT, which has specific recommendations on bug-fixing.

c) Looking at the collated entries, the only time where Mystical World even pops up is:

This is a pretty insignificant contribution and isn't likely to be causing your TPS issues.

If you can replicate this without MCMT, please file another issue.