Not really. They only kill idle processes, and, (if they're loaded with ads) slightly defeate their own purpose. My best advice is to:
1. Moderate your screen brightness.
2. Clear all recent apps before playing a game.
3. Avoid weak WiFi connections if possible.
4. Disable things like BlueTooth or internet (if possible).
5. Play while your device charges.
But there are many more variables at play here. This includes things like your devices specs, carrier, as well as many more things. You should actually avoid these apps. I've decompiled some in the past, and found things like adware and malware!