I will be specific about my complaints that started immediately after Yosemite upgrade: Graphic glitches in google voice and gmail, bizarre cpu usage out of now

I will be specific about my complaints that started immediately after Yosemite upgrade: Graphic glitches in google voice and gmail, bizarre cpu usage out of nowhere, two-finger left swipe changed somehow to be more "sensitive", wifi randomly disconnecting and reconnecting out of the blue, shorter battery life, a "slowness" that is hard to describe but noticeable to me because I use my computer the same way every day, two full "grey screens of death", which I have never experienced in all my time using OSX, "slowness" on memory swapping to the point of beachballs, the list goes on. All of these started immediately after Yosemite upgrade. I have been a long-time OSX user, and have never had a full-blown systems stops until now on any machine I have ever owned from Apple.