LT3015 negative regulator output voltage gets dip during pulsed load

Below is the schematic of LT3015

POT R217 is tuned for -2.66V output voltage, When the load is applied for 50uS pulse the output of LT3015 is dipping and raising after approx 800uS. below is the scope snap shot

Note: Yellow trace Logic "0"  indicates load connected(Load current approx less than 5mA) and Green trace indicates LT3015 regulator output.

  

I want stable -2.66V at regulator output during load also, Please suggest some circuit modifications to achieve stable output