Hi,
h.265 is a newer and more efficient compression format compared to h.264 mainly to reduce bandwidth from live streaming sources. That means also that h.265 need more cpu power for processing data. As of today Netcam Studio do not support h.265. An h.265 compressed file will have a smaller size than an h.264 compressed file with the same quality. However, to the cost of increased cpu load.
-Henrik