"He who marches out of step hears another drum." ~ Ken Kesey
At the sign & print shop I managed, we would work in a smaller proportional scale. 3x6' banner would be 6"x12" in Illustrator. This would make working with effects much less resource intensive. We would let the RIP handle the scaling up before output. We would rarely work in anything close to final scale. You may already be doing this, if not try it.Second option would create the effects on the components in photoshop then drop all the components into inDesign, still at a smaller scale. Sometimes you need the effect on a large portion of the layout so it may not be as easy as the first option.
I know in Corel I learned to make the effects a bitmap and you can adjust the size not sure about AI though But I have learned the faster the hard drive the better. Your system is very similar to mine. Except video and hard drive.