For 8GB RAM and low end graphics card (GT730), settings that work fine up to turn 125 on duel map 3 civs (won the game on this turn):
Resolution 1920X1080
Rendering set to low
Terrain set to low (major factor)
Buildings at medium
GPU processing animation turned off (although the tooltip mentions "speedup", this setting seems to greatly increase lag.)
All post-processing effects turned off (depth of field, colour correction, bloom, etc)
Slow AI off (not sure whether this setting can speedup gameplay)