I did some tests with the new and old x265. I report some data, while the terminal output is attached in test-x265.txt. I used a 5 min video in h264 4.2.0 but good quality. Size= 471 MB. x265-10bit: CPU 50-80% (multithread) 27.5 fps file size 46 MB x265-12bit: CPU 50-80% (multi) 25.5 fps file size 45 MB x265-Hi: CPU 80-90% (multi) 10.6 fps file size 1.7 GB x265-Lo(w): CPU 40-70% (single/multi) 34 fps file size 67.5 MB HEVC-vaapi CPU 0-50% (single) 85.8 fps file size 117 MB (I could not see the GPU engagement) Only in x265-lo do I perceive a small decay in quality compared to the original. All others are comparable. For me a great news (thanks Andrew!) is the exploitation of multithread; on the terminal you can read the sentence: "Thread pool created using 16 threads" I have a CPU 8c/16t. The only thing I regret is that the new x265 drivers introduce a CinGG build delay of 15 min. Before my entire compile was 5 min, now it's 20 min.