Steps to reproduce:
We updated from 3.4.3 to 3.4.5 (13.01. 00:45) and got serious performance issues.
Result:
See history syncer usage in
We have delays in graphs up to 15 minutes after HH:00 and with the history syncer processes on 100%, so perhaps it has something to do with the trends. See

Expected:
Like before 13.01. 00:45, nearly no history syncer usage, just some peaks still below 50%.