Futaba 3PM FASST low response time

Hello, i run my mugen MBX5T with a Futaba 3PM FASST radio.
I've standard servo on my truggy, so i run the radio in PPM mode (not HRS), and i find that the response is very slow, (i give trottle and have long gap before the controller react) when my truck is far from me.
I've an MGM16018 with a NEU 1515 1Y.
I've a nitro savage with digital servo and i run it on HRS mode and the response is very faster than my brushless truck on PPM mode.

Have you experiment this problem??

And if i put digital servo on my brushless truggy, can i run HRS mode with the MGM controller???

Thank you