Hey! 
See attached for reference - system specs below.
2 questions about this.
1 - I noticed that as I increased polys in the scene my system and GPU ram increased but the system ram increased at a greater rate. It wasn’t until I found a utility to show GPU memory use that I realized that the viewport/system sluggishness was system based - I obviously have plenty of GPU ram left. What’s going on here?
2 - Until above observation I was thinking of upgrading my video card but now I’m thinking I need to increase system memory - probably doubling it to 16GB. Agreed? The video card would have been cheaper! To upgrade the memory means new Processor, MB and ram. Oh well! LOL
System:
Intel Quad Core 2 Q6600 2.4Ghz
Abit P35 Pro - 8GB Ram (maxed out for that MB)
Evga GTX 660 3GB Ram
Windows 7 Pro SP1
3D Max 2015