144Hz test stutter problem?

[Omie]

I recently purchased a Dell S2716DG and built this PC: https://pcpartpicker.com/list/dNhpVY

 

When I run the 144Hz test at http://www.testufo.com/#test=framerates on Chrome, it tells me "performance warning potential browser stutter occurred." And then it tells me stuttering is occurring I'm not sure if this is normal or not. The site says I'm getting between 142-144 fps. I've tried disabling Gsync/Vsync and closing every open application and tab and still have the same stutter warning..

 

Does anyone know why this is happening?

[OwnagePotato]

Yep the same thing is happening here. 140-144 fps still. +1 stutter. dunno why.