We present measurements of the evolutionary timescales of speckles around adaptive optics-corrected PSFs. We placed a SELEX SAPHIRA HgCdTe detector behind the SCExA0 instrument at Subaru Telescope. We analyzed the behavior of speckles at radial distances of 2-8 A/D away from the diffraction-limited PSF in H-band (-1.6 m) images collected at 1 kHz framerates. Speckles evolve with a variety of timescales, and these have not previously been studied at near-infrared wavelengths. Ultimately we would like to image reflected-light exoplanets, which necessitates a fast speckle control loop. Based on our measurements, we calculate the parameters of an optimized control loop that would enable such observations.