+ super lowpoly player models according to distance as option in video
+ drawgun 0
+ disable some hud info
+ less walk animation frames(may be)
+ simple hitboxes
I wonder if you've read the article you just posted. He stated that GPU was loaded for just 15-20% of it's max capacity.
Even if your player model is being rendered as you state it is just maybe 2-5% or polygons you would see on screen so basically nothing.
I don't know exactly. But all vertexes(polygons) should handled by CPU before they going to GPU. So less vertexes(polygons)->more free time for CPU and less motherboard's RAM calls.