What does "Increase Contrast" option change?
I can't comment specifically on the Contrast setting, however there are various defaults you can enable from the terminal that will speed things up - specifically window "show" delays.

Browse some of these scripts:


https://gist.github.com/brandonb927/3195465
https://gist.github.com/maxfenton/c5a316f4254d27b18cf3


You will find various commands to reduce the delay between showing windows, 

Example:

To speed up mission control you could do:

defaults write com.apple.dock expose-animation-duration -float 0.1
killall Dock


This will reduce the animation delay to .1 second before showing mission control

Its possible some of these settings get tweaked when you go into enhanced contrast mode.