The CPU usage percentage has nothing to do with speed increase or decrease! It's all about the raw power, efficiency, and the increased IPC of the CPU's architecture, and if you have enough clock speed to run the game without the gpu being the bottleneck.
[color=#3366ff]CPU: Intel Core i7 4790K OC'ed @ 5GHz[/color]
[color=#339933]GPU: MSi N580 Lightning Extreme 3GB[/color]
[color=#cc3333]RAM: CORSAIR Vengeance Pro 16GB DDR3 @ 2666MHz[/color]
[color=#333333]HDD: Samsung 840 Pro SSD 512GB[/color]
[color=#6666ff]CPU cooler: Noctua NH-U14S w/Noctua NF-A15 PWM 140mm Premium[/color]
[color=#ff3333]MOBO: Asus Maximus VI Hero LGA 1150 Z87[/color]
[color=#cc3399]CASE: Thermaltake Urban T81 Full Tower[/color]
[color=#339933]GPU: MSi N580 Lightning Extreme 3GB[/color]
[color=#cc3333]RAM: CORSAIR Vengeance Pro 16GB DDR3 @ 2666MHz[/color]
[color=#333333]HDD: Samsung 840 Pro SSD 512GB[/color]
[color=#6666ff]CPU cooler: Noctua NH-U14S w/Noctua NF-A15 PWM 140mm Premium[/color]
[color=#ff3333]MOBO: Asus Maximus VI Hero LGA 1150 Z87[/color]
[color=#cc3399]CASE: Thermaltake Urban T81 Full Tower[/color]