Well, I had experienced this before. My friend told me to convert my
presentation to Flash, I found it works very well to reduce my bulky
PowerPoint presentation upto 80%.
1. zip it if you need to upload it
2. try to avoid embedded videos/audios and using bmp as the pix. Png
is the format I like most, small in size and good in quality.
you might have some graphics that are a high (print) dpi. If you use the
compress image function it brings all the dpi's down to ether 200 or 96. It
also deletes the cropped area of a picture.