FMS3 Recorded stream playback speed too high

Hi, is there a change between FMS2 and FMIS3 in stram.play() ?

I need to publish a stream from the server which has been recorded with FMS just before.
When I play back this stream on the client, it runs much too fast and pauses from time to time to reload
the next video data and then runs full speed to the next pause.
I tried setting bandwidth limits with no effect.
I tried different fps settings when recording with no effect.
I tried different fps settings when playing back with no effect.

On FMS2 this worked nicely. (No, I can't switch back.)
I suspect the problem to be some server side buffering or so, but I can't find a solution.
Can anybody else ? Maybe some pointers to the server configuration docs ?

On the server:
myStream = Stream.get( playVideoName );
myStream.play( "streamnametoplay", 0 );

On the client:
ns = new NetStream( netConn );
video.attachNetStream( ns );
ns.play( 'streamnametoplay' );

Thanks for any hints