Macbook Pro Mid 2014 stuttering and small lag spikes @ 4K 30Hz with HDMI 2.0/1.4b
I have a new 15 inch MacBook Pro. it has 4 thunderbolt ports on the sides. 2 on each side. no USB ports. so I bought an adapter for it. its  called a lention and has 4 different ports,3 usb an one lightening so I could plug my mouse in to it.i  began experiencing stuttering on my games and video. every 4 seconds it would stutter. my frame rates were going from 60fps to 30 fps and back an forth causing the stuttering.i unplugged it(the lention adapter) from my MacBook Pro an stuttering stopped!I went too the apple store an bought a different one(white one with just 1 USB port)an the stuttering has stopped completely.just wanted to share this in hopes it will help.