I'm using AVI Mux GUI 1.7.8.3 The Alex Noe build. When I run it, it only uses 1 to 3 % CPU, as viewed in Win Task Mgr > Performance. As a result demuxes \ muxes take a very long time.
I'm running an i7 4790 & 32 GB RAM, so there's plenty available. I'm also running Win 7 64 bit. The app itself...