Performant[1] (comparative more performant, superlative most performant): (jargon, chiefly computing) Capable of or characterized by an adequate or excellent level of performance or efficiency.
"Ours is a performant network monitoring and systems monitoring tool."
"This software is ten percent more performant than its predecessor."
Yes, but somebody adding it to wiktionary doesn't make it a word. It just seems lazy to make up new words rather that taking the trouble to use an existing one.
[1]: http://en.wiktionary.org/wiki/performant