Yes, PERFORMANCE is a Scrabble word!

Letter values in Scrabble US: P 3, E 1, R 1, F 4, O 1, R 1, M 3, A 1, N 1, C 3, E 1.

Is it a valid word?

PERFORMANCE is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a dramatic or musical entertainment
the act of presenting a play or a piece of music or other entertainment
the act of performing; of doing something successfully; using knowledge as distinguished from merely possessing it
any recognized accomplishment
process or manner of functioning or operating

Also: public presentation, carrying out, carrying into action.