Regarding the lags
I guess its not the problem with the app.
At normal usage, there is very less work for graphics and so it never comes into play but when you are playing a graphic intensive game, it needs a lot of graphics and the phone cannot render the gpu.
So when you enable force gpu rendering, it allocates more graphics support and also reduces the lags.
You can try clearing RAM and Used applications before playing games and also switch off internet.
Switching off internet reduces the advertisements on apps by which you can reduce some lagging.
Hope it helps and it works.