Blazing Fury causes horrible lag in the Jack fight, but also (a bit less horrible) lag in the Cat God fight.
In the Cat God the lag is minor enough so that it’s possible to see that when this happens, Blazing Fury cooldown resets.
(Two signatures in use just to see the difference in shared cd. No getting such difference between chaos and shotgun in that fight/setup.)
Lag starts from taking the first damage after having used Blazing Fury.
I’ve had some new lag spikes in DA too with hammer, at least some happening after using Blazing Fury, but not sure if that’s just coincident.