During simulation time stop


I have programmed with robotstudio a pick and place cycle. The robot is pickung up workpieces and put it down to another place. When I simulate the cycle, everytime when the robot is picking up a piece the simulation and also the time stop. After two seconds the simulation goes ahead. When i record the simulation with a video (with robotstudio) there is no delay. My question is: could it be possible that my pc is to slow for the simulation?  Or can this delay have other causes?