Despite having a lot of the ball, the Magpies lost the game 2-0 at Selhurst Park on Wednesday night.
Howe said in his post-game press conference: "We were very disappointed with the performance, from the high of Tottenham to the low of tonight. We were disappointing in most aspects of our play.
"We have to take responsibility for that. Maybe the gap between games didn't help us on reflection but still we knew that gap was there and we had to perform better than we did today. It is a missed opportunity for us."
Howe added: "The first couple of minutes it looked like we were in a good place. The first half then unraveled into an uncomfortable feeling where we were not firing on all cylinders.
"We were not playing with brilliant rhythm, we got in at half-time at 0-0 and we were relieved to do that. I anticipated a much better second half. We probably were better in the second period up to 60 minutes but the two goals we conceded summed up our performance really."