Performance regression, Animator uses 99% of cpu time

When I activate the object at runtime which has an animator component, a big lag spike happens(so big that the whole game freeze itself for a second on my Nexus 6p). It happens in both the editor and player(Android, iOS, WebGL is all I've tested). Note that it only happens on first run of the game, and also note that all objects are present in the scene and just activated, there is no instantiation.

I reported this as a bug(case 800718) like a week ago but nobody checked the report yet and this is very much affecting my production as all of my projects have this problem.

Using Unity 5.3.5 here, this is a performance regression obviously, and the QA should really do more tests before publishing...

Anyone else having this problem? Any workaround? This is how the profiler looks: