The first thing I'd suggest is that you have applied all three RH8 patches. It could be that your project's CPD file has become large. You could also ensure that the option to delete and recreate it is checked. See here for further details.
I'm on 8.02.208.
I solved my problem by deleting a lot of the Unused Files. This got the file, when zipped, down to 54mb.
However, now I have a lot of broken links and the message says "You cannot create a file from a missing bookmark..."
Today I went in a checked the tickbox: "clear .cpd file before opening any projects."
When do you recommend getting rid of unused files and is there a script to do this?