Honestly gaming boosters don't do much. I know in low frame rates, gaming mode can help slightly to smooth things out, but that's about it. IDK about razer cortex, I've run it, but didn't really see any gains (mind you I probably wouldn't notice the minor gains from game mode either).
If your a little low in frames, I'd just configure the settings to minimum settings, and _maybe_ run game mode. Something with true access to the OS, is going to probably be more effective than something that doesn't (in terms of controlling hardware access). But the most obvious and effective thing to do is to turn down intensive effects like motion blur, shadows, anti-aliasing etc and lower the resolution.