Multiuser app sync problem

hi
im using red5 to create a chat but currently im having problems with sync between clients , you can see a video demo here : multiuser demo

the demo runs ok because all the clients are running locally but when someone with a very slow computer connects the frame rates for that client are slow compared to a client with a new computer and the result is that some penguins move faster than others (better computer better performance in the swf)

so how can i fix this ??

some of my vars that might be of relevance :
aceleration =.5
maxSpeed =15

thanks