encode speed low

[Former user]

my cpu model is Intel(R) Xeon(R) CPU E5-2699 v4 @ 2.20GHz, 4 core 4 threads, I use 1280*720 yuv of 438 frames, I have appoint thread nums is X265_MAX_FRAME_THREADS, my cpu using 400% already, but finally cost 20s, the same yuv file x264 only cost 3s.