That’s really odd - we believe its a Wifi issue with the ESP8266 since we see packet loss there, but not via USB. Could you try setting your gains with USB and a computer?
In general we noticed that dropping the ROLL_P gain and increasing the ROLLRATE_P gain is better for racing - could you help us testing that?
One experiment to try is to drop ROLL_P to 3 and increase ROLLRATE_P to 0.25 (same for pitch). You still need to tune, that’s just a starting point. I would be interested to know if you get that to a satisfactory result, because then rate mode should be a lot more stable.