Hello,
this is likely because of the animation of the crowd.
This is a recurring request, so I just added for the next update the possibility to disable it in Settings -> Video -> Advanced.
Meanwhile, you can turn off the crowd animation by changing this line in your Tennis.ini, under [3dEngine], from :
CrowdAnimation = 1
to :
CrowdAnimation = 0
(HowTo =>
topic19-32161.php )