The HMC784A data sheet indicates 112 ns switching time (10% to 90% RF) with VCTRL & VDD of 5 V.
I'm getting much longer switching times, on the order of 2 us. I'm using it at VCTRL & VDD of 8 V. I assume this is GaAs gate lag? Do you have any switching speed data for 8 V operation. My drivers are plenty fast enough.