Simple x264/x265 Launcher is a straightforward GUI front-end for the x264 H.264/AVC and x265 (HEVC) encoder. Simple x264 Launcher can use the 64-Bit version of x264/x265 with the 32-Bit version of Avisynth.
This way, you can keep on using your favorite 32-Bit Avisynth plug-ins (e.g., DGDecodeNV) and still benefit from the speed improvements of 64-Bit x264. And of course, you can use x264's built-in LAVF/FFMS input instead of Avisynth just as well. Moreover, this program provides full batch encoding support. This fact means that you can run several encoding jobs in parallel. Or you can let them run in sequence - one by one.