High idle CPU usage on servers compared to earlier versions

When migrating from 1.13 to 1.14, the Java Minecraft server saw significant performance decreases. I was hoping 1.15 would see improvements back to what 1.13 was like, but that doesn't seem to be the case.

I ran a test by switching my server from 1.14 to 1.15, then 1.13 to show the relative differences in performance. Attached is the CPU usage chart from the Linode instance I use to run the server. The sections labeled 1.15 and 1.13 are brand new worlds with no players logged in.