Repeat the clean boot process again but this time don't re-able everything you had disabled, just re-enable two or three and reboot.

If start up is still fast, then you know the problem isn't the two or three you just re-enabled. So you could now re-enable two or three more and try again, etc., etc, etc.

If start up is s-l-o-w, then you know the problem *-is-* one or more of the ones you just re-enabled. So disable one of the ones you just re-enabled and try again.

In other words, process of elimination.