Is it possible to go back to a previouse OS after uptading to the newest one?

I updated my Galaxy S5 to the new Lollipop 5.0 OS and found it causes problems with apps that use a lot of computing. Specifically in Real Racing 3, the phones touch screen and rotation sensor freeze for a couple of seconds leaving you with no control over the phone. Also it takes longer to start up apps of any large size. Therefore the previous OS was a lot better, along with other odd features like the operation of the top pull down screen. So I would like to go bake to the previous OS.

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