找到了一篇

http://www.extremetech.com/computin...-expectations/2

Compared to x264, even on the –veryslow preset, x265 encodes take noticeably longer — our Ivy Bridge 3770K encoded the same file in H.264 in 129 seconds as compared to 247 seconds for H.265. Keep in mind, however, that this is very, very early software.

只能希望未來有改善了