Issues with working with Drawings

I've been experiencing probelms with certain drawings and models over the last while.

I find that when i work with one of my specific assemblies in particular of a large structure in drawing format that when i move about sheets or try to move views on the page the computer pauses to load a lot and when i try and save it can sometimes crash and shut the program down. if i'm luck enough to save the drawing and save as a PDF which i need to do for my job i find that the PDF can be over 5000kb in the folder where as other similar detail ones are only 719kb. This then causes problems for printing and i often find i block the printer,

Can anyone shed some light on what i may be doing wrong?

The assemblies are not that complicated although big and i have produced bigger and more detailed ones with no problems,

Thanks

SolidworksDrawings And Detailing