Good computer + Good internet = Lag???

Hey guys, i have good specs on my computer, really good internet 50 mbps download and upload speed, but i still get bad performance on csgo. It is not unplayable, but it is not smooth at all, really difficult to headshot when the screen freezes for half a second and skips a lot. I cant seem to find out what the problem could be, here is my computer specs and result of a test on pingtest.net

http://ift.tt/1OVWKOk

Specs:
Windows 10 64-bit
Processor: Intel core i5-4440 3.1 Ghz
Graphics card: Nvidia GeForce gtx 660 OC 2gb
RAM: 8GB

Thanks for help

Good computer + Good internet = Lag???