Jean-Philippe Mateta and Marc Guehi scored as Palace won 2-0.
Glasner said afterwards: "We are pleased with the three points and the clean sheet. We have to be critical of our performance in the first half. It was a little bit louder in the dressing room and the players showed a good reaction. We have to improve our performance.
"We were more aggressive. I told the players and showed them clips about tactical adjustments. We were just jogging about the pitch and this is what we showed them. We did it better in the second half but still not our top level. We can't be happy with the performance in the first half.
"The whole situation was great. In this situation, Sarr was in the right position and we need runs in behind. First half we didn't have anyone in behind. We know when Mateta gets the ball in the box, it's very often a goal.
"We had the worst start in the Premier League history of Crystal Palace and now it's the opposite. We are always humble. We are compact in our shape most of the time but we need to improve our performance and reduce our easy mistakes."