Originally Posted by RazorSharpe

When I encode server side, I simply use a service ( Cloud Video Encoding/Transcoding Software as a Service | Brightcove Zencoder )

However, it looks like you want to convert locally and for that I use:
Video Software | Download Movavi Video Suite ? Best Video Creator!

Them claiming to be fast isn't a gimmick, I've tried almost all the converters that they are pitting themselves against here:
Movavi Video Converter ? Download | Fastest conversion of any video format
and movavi is in fact a whole lot faster ...