That sounds strange. Unless you're doing a lot of performance expensive stuff in your test scripts, you should easily be able to reach a higher RPS.

Also, are you comparing a single Locust process to Gatling? Since Gatling runs on the JVM, it would be more fair to compare it to a Locust cluster with one locust process per processor core.

This seems wrong. Make sure you're following the guides in their documentation (run one locust slave instance per core). But that aside, 200 RPS is way too low for a locust instance. I use locust for loads 100k+ rps, if 200rps per host were my limit I wouldn't be using locust.