Performance regression after "Abstract QWidget focus chain management"

There seem to be a huge performance regression with the current latest code in dev (e7362764d4931f255d2377462df8ac7a0d4e7c84).
I built both my project and Qt in Debug.
It's fixed if I revert the following commit:
58d5d4b7c2faaeaa2c2ccdabb3da6d37f9db880a Abstract QWidget focus chain management
(I also had to revert 079578eadd1ffe593bf8afbfe7c401b7e3176c63 first to avoid conflicts).

A setting dialog I use with multiple stacked widgets takes 10 seconds to open when it before took 1 second or less.
So it seems this change introduces a performance regression, might be worth reverting unless it can be fixed before the next release.

CC axelspoerl