AMCL freeze

Hi all, I'm using the AMCL node to localize my robot, I launch the AMCL and localized the robot whitin rviz (using default configuration *rosrun amcl amcl scan:=laser*), I see the particle cloud and all seem to work fine, then when i start to move the robot the particles freeze out. The AMCL node don't report any issue but still it doesn't publish anything. I was trying different configurations and i realize that if i set the maximun particle number up to 500 the node work fine and it doesn't freeze out, for any particle cloud larger than that the AMCL stop working Any advice?