Unhappy [Q] Replaced glass screen, now apps/ device runs in slow motion?

Hello, firstly my apologies if this is a common issue that has been answered 100 times, however I cannot seem to find it on this forum.

I have replaced the cracked glass on my galaxy s4, previously no issues with the touch, display at all running the latest 4.3 cyanogen-mod version. Now suddenly after turning on the phone the apps and general navigation will be in super slow motion, ie- takes a couple seconds for a menu to fade in to the screen.
Has anyone seen this before? Do I need to completely wipe my phone/reinstall my rom? Or could this be an issue with the digitizer, the screen is responsive as far as I can tell, with no dead pixels.
Thanks!