Lag in packaged "game"


When I play my game/archviz scene in the viewport it runs very smoothly and great but as soon as I’ve packaged it and play it there is some very disturbing lag (I have a very powerful computer). Can I do anything about this? I can add that I’ve had some " Texture Streamin Pool Over…" messages recently. I think my texture pool size is set to 3500. Any help would be appreciated.

Thanks in advance!