Recording Problems

I am having problems recording audio in FIMS 3.5. About 20% of the videos recorded appear to fast forward part way through the video. I understand this occurs when there is lag between the audio and video that is sent from the client to the FIMS server. I have tried setting the parameters in the <RecBuffer> section of the Server.xml file to sufficiently high values to offset the lag but the problem is still occurring. Are there any other areas I should be looking at to solve this issue?