Macbook Pro lags when dual screen is connected My mac acts weird sometimes when I connect it to two of my 1080p screens. The computer will become extremely lagging to the point where it becomes unusable. Things will recover once I unplug either one screen or both screens. (My MBP's screen is closed, power plugged in.)

I didn't have these issues before, therefore my guess is that there is no hardware compatibility issue. However, I think that my gfx should also be adequate to support two 1080p screens.

Does anyone have any idea what could be happening?

Specs:
Macbook Pro, 15 inch (Mid 2014)
2.5 GHz Intel Core i7
16 GB 1600 MHz DDR3
NVIDIA GeForce GT 750M 2 GB

** I have been monitoring my RAM and CPU usage through Activity Monitor when these lag moments happen and they were barely utilised.

** Also ran an Apple Hardware Test but no issues were found.
Try a different HDMI cable. Not all HDMI cables work well with Macs. Make sure that you get one of a decent quality, those are usually better.