This does seem to have helped with Safari issues, however, my Mac turned itself off today. Turns out it got too hot using Flash. This has only been happening since 10.10.3. (I got Macs Fan Control to see what temp my Mac is running at, and when I started up after it shut itself off, and it started running video again, I watched the temp and it was hovering around 88ºC...I think it shuts down over 90º).
So, some months ago, I was about to do a clean install of Yosemite and was trying to avoid installing Flash. I tested how much CPU Flash uses on my Mac, Safari used the least CPU power (fastest), Google Chrome (using it's Flash emulator or whatever) used a lot more CPU (I think it was like 20-30% more). I don't have Chrome, I hate google, so deleted it when I found Safari to be better, (also hate Flash, but, only way to watch some video still), but, anyone know, has Google made improvements to Chrome's speed/CPU usage recently? Maybe I should try it again?