Goals from Luke Chambers, Marcus Tudgay and Garath McCleary condemned Palace to a fifth straight defeat on the road and left them stuck in the bottom three.
Burley said: "We never got going and gave away horrendous goals away. The first one was a free header, there was no defender marking which there should have been.
"We changed things at half-time, put a striker on to try and get at them and then within a minute we're 2-0 down.
"It was a hard game after that and although we huffed and puffed, we didn't do enough to get back into it. Julian Speroni has made some saves but some of our defending was very poor.
"Forest looked lively and bright, they haven't had a game for a few weeks and they looked sharp. But the manner in which we gave the goals away for me was very disappointing."