OK I've tried that game, front line 2, for about 10 minutes. Got bored with it tbh. So moved onto playing asphalt 8 then pvz2 for a good half hour.
Now the screen does get warm/hot but not so that I can't touch it. I noticed zero lag.
It is possible that as I'm using a custom kernel that has had the governor settings altered that this has under clocked/volted my phone so it's less noticeable than yours. Of course this is a balancing act if you under clock it too much it could lag. If you over it it'll heat up too much.
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Could you point out your custom rom and kernel so I can make my own experiments with that?
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