Presenter PDF running slow on web server

Hi,

Has anyone encountered any issues concerning a presenter video that downloads slow, starts up, continues to download, but also affects the ability to advance or rewind the presentation? 

Have produced 4 modules ranging in size from 15 GB to 48 GB and placed them on a staging web server. The latter two which are 36GB and 48GB in PDF format appear to download slower on our server and although they run, the user cannot advance or rewind at will.

Can anything be done to improve the 'efficiency' of the download.

Are there other options such as HTML5 and if so, what would my technical team need to know to pursue this option?

Thanks.