After I updated to 8.4 the timeline respone is very slow, sometimes it takes 1-2 sec for 1 frame forward, scrubbing is laggy too....absolutely not usable. Downgraded to 8.3 everything seems ok, with normal response times.
I tried it on a MacPro 2009, SSD Drive, with Yosemeite 10.10, 10.10.2 and 10.10.3, local and shared storage, but no difference.
Is there a clue?