The Xing (pronounced "zing") MP3 encoder has, for a long time, held the crown of being one of the fastest MP3 encoders. Of course that comes with a price, and quality isn't on par with other - slower, but tuned for quality instead of speed - encoders like FhG Slowenc (Audioactive) and LAME.
While Xing has always been considered an encoder with terrible quality, that rumour was proven untrue after a listening test compared an old version of it against other MP3 encoders and it ended up not even close to last place.
- Encodes .wav to MPEG-1 and MPEG-2 layer 3 audio
- Encodes bitrates ranging from 28 to 320 kbps
- Variable Bitrate (VBR) encoding support
- High Frequency Encoding support (up to 20 kHz)
- Low data rate support
- Several times faster than most popular encoders
- Automated batch processing
- MP3 playback capabilities
- GUI based and command-line encoder front ends
Recently, Real Networks - owners of the Xing assets after they bought that company - decided to release the Xing encoder under an open source license. https://helixcommunity.org/viewcvs/cgi/viewcvs.cgi/datatype/mp3/codec/encoder/