Try looking into the redraw options and what not in the work environment settings. Simplified 2d settings are available for pans, zooms etc That should help speeding things up a bit.
Turn off vectorial hatching while working for on screen display. Along with line width, handles, etc, anything you don't need to have on all the time.
Make clever layer combinations to focus on working on different disciplines (MEP, interior, structural, etc), where you turn off layers that are not needed.
Close windows you are not currently working in (elevations, sections, worksheets, schedules).
Be careful with complex profiles that have holes inside them, this will slow down the projected cuts in plan view.
Be careful with objects that generate projected 2d views, these can slow things down too. If possible create seperate layers for those, so you can turn those specific elements off when working on things if you don't need them.
You say you have a lot of module files, if you cut up the building in to small 'workspaces', you should be working in small project files which all come together in a big file where you would preferably do almost no actual work.
Good luck! Sounds like a great project to work on.
Erwin Edel, Project Lead, Leloup Architecten
www.leloup.nlArchiCAD 9-26NED FULL
Windows 10 Pro
Adobe Design Premium CS5