Mine also. It's a combination of a way-stiff throttle pedal (which I get, you don't want to fall off a rock and floor the thing by accident) and the butterfly position v/ pedal position. On these electric throttles, the % the butterfly opens is mapped to the pedal position, vehicle speed, rpm, wheel speed etc. It's not linear.
On my previous '10 Mustang off-idle the butterfly was factory set to only open 55% even if floored... until the rpm and wheel speed (front wheel) agreed with the map setting. I had a custom tune fix that.
I thought I saw another thread on here discussing changing the spring or potentiometer or something similar on the pedal to try and fix the "lag". (without getting into the computer mapping). I am going to look at the pedal this weekend. If I come up with anything practical, I'll post it.