What card/cards are you using?
Check this site and see what the benchmark for your card is and check that to something newer:
https://render.otoy.com/octanebench/(You can also download Octane Bench and get the actual benchmark for your setup).
Another thing to think about is VRAM, if you feel limited in the VRAM you have then upgrading could really help out.
1080 has 8 gigs, one of my comps has a 690 which is only 2 and I need to optimized some of my scenes to be able to load into the 690.
Intel quad core i5 @ 4.0 ghz | 8 gigs of Ram | Geforce GTX 470 - 1.25 gigs of Ram