MPU-6050 DLPF and acceleration issue

Hello

I working on the rc helicopter control system, which stabilise this model with gyro only.
My problem is simple, when I fly with this helicopter in higher rotations I observing not so precise stabilisation. I mean during fast flips, rolls it drifts little bit with time. It seems like it is non linear or something like that and acceleration affecting gyro values.
BUT if I set DLPF to 20Hz, it is without any issue and very precise. But problem is, this filter is so slow for my needs.
Higher DLPF I set, worse precision in flight.
With DLPF at 98Hz it is fast and still with good filtration capabilities but not as precise as 20Hz. It flies like with high cross axis error during manouvers.
With DLPF at 256Hz + my own filter result is even worse in terms of precision.
Same with more MPU units.
I have to fix this problem, its very important to me.

Somebody know, where could be a problem?
Thanks