Esc misfiring?

[brushlessboy16]

So I have a Mamba monster in a slash with an aveox motor geared for about 40mph on 4s lipo.. really conservative. timing set to 10 .. bear with me as i describe what its doing


You guys know at very low speed how the esc changes switching frequencies,

at the moment the frequency changes my esc loses time with the motor and just sits there and stutters.. if i give it more throttle it just kind of skips over that bit and continues on fine.

I dont think its cogging because the batteries are plenty powerful and it gets better the more I pull the trigger..

What is this and how do i remedy it?

Thanks,

Ben