I could never find a Live performance of this track (possibly my fav among Satriani's works).
Was it ever played live? If not - is there a reason for that?
This is the best place to find if a musician has played a song live. It doesn't look like anyone recorded him playing it live. My guess - this song was recorded for the Super Mario Brothers movie, released in 1993. Also released in 1993: The Extremist. My guess would be that he recorded Speed of Light in late 1992 - maybe even as an extra track that never made it on The Extremist - then released The Extremist a few months later, and decided to tour using those songs. Keep in mind this is considered by some to be Satriani's prime, and being just on the heels of Flying in a Blue Dream, there probably wasn't space on any tour for that song.
After that, it was likely lost in the shuffle.