After a while the browser starts to lag

[Admini]

Yes, full sync, but I only use one computer.
And yes, there were abnormally shutdowns when I was overclocking, but the browser did not start lagging after that. Last time (about a year ago), he also lagged, but I don't remember abnormally shutdowns.
Again, clearing the history solved the lag problem, so I doubt that the problem is in the corrupted file.

Yes, this may be a Chromium bug.
Next time you can send us the "History" file for analysis if convenient.