The phrase "appalling performance" means that someone's performance was extremely bad or terrible.
Sentences with «appalling performance»
And although we've lost «only 2 games», it really doesn't tell the whole story about how appalling our performances have been. (justarsenal.com)
Labour's appalling performance in Scotland and its inability to win more than a few marginal constituencies in England certainly needs explanation. (theconversation.com)
It's always good when the weekly narrative gets shaken up a little bit; after several weeks of truly appalling performances from Ed Miliband, this week it was David Cameron's turn to put in a bit of a shocker. (politics.co.uk)