A few things are recommended in order for a virtual presentation to work faster.
1) Keep less amount of objects on a scene, if you have same material keep all the elements either grouped or welded by material.
2) Transparency reduces the speed of a scene, change from 24bits to 8 bits RGB trasparency blending, in the scene/render materials option window.
3) Water effects are very nice, but if you have a really large scene it may slow down the system, use the water and bloom effect wisely.
4)Better hardware always helps, so a good video card with 500mb video memory or more will give you a better results