I can't answer your questions, sorry for writing a reply nonetheless

I really don't need the docs because I can always look up on the net for them.

The advantage of the local HTML documentation is that it always of the same version as the modules you are using on that machine. If you go to search.cpan.org, it will show the newest version of each module by default, which can differ significantly from what you use.

So if I were you, I wouldn't worry too much about the time the HTML generation takes, since module installation is a relative rare operation. (If you deploy the modules to many machines, this might not be the case anymore; then one could start thinking about synchronizing directory trees instead).