Fast Graphics look fancy

Summary
I was testing 1.8 pre-releases in my survival world when I noticed I had a lot more lag than usual, then i noticed graphics were on fancy, changed to fast but...

What I expected to happen was...:
Changing from fancy to fast should change some textures and REDUCE LAG.

What actually happened was...:
Everything shows as fancy graphics (the only texture that actually changes was tree leaves)

Steps to Reproduce:
1. Click graphics button
2. Compare