Experiencing lags using the window drag method
I own a 2014 15'' MBP GT750m and followed the build of matthieuv to make the eGPU accelerate my Retina display. Although it ran pretty well for some days, I had issues during Windows startup and this finally destroyed my bootcamp partition.
I decided then to test my setup with an external LCD, where everything is working fine now. I still have POST issues but Windows starts correctly (100% success rate). The build seems to be solid.
Now I would want to try the famous "window drag method" with a fake display. I don't have the equipment to simulate a fake display so I simply tested the method by dragging the window of the game Overwatch from my external LCD to the Retina display. It worked fine...in appearance. I have some performance hit (which is to be expected) but Overwatch is using the GTX 1060 (eGPU) on my Retina display.
The problem is that it feels really laggy. I locked the fps at 60 for both configurations (on the external display and on the internal display) just to compare. On the external display everything works fine (no lags) whereas movements are not smooth at all while using the internal display although I am running constantly 60 fps in both configurations.
What could cause this effect? Is it possible that latency creates these lags or does it have something to do with the iGPU or dGPU which displays the image? Does someone have an idea?
Thank you in advance for the help 😉
Okay, It seems that it was related to the external monitor itself. I ordered a ghost adapter and everything runs fine now, except I have now very low performances (2 times less than obtained through the Optimus route)...
I think it's time to end this thread finally. I got an explanation of what is going on.
Laptops always have an on-board iGPU which will display the image on your screen. While using an external graphic card, the latter renders the frames (images), sends the information to the iGPU (CPU), which will display the images on your laptop screen. If you run games in windowed mode, your iGPU will have to display your game but also what’s happening in the background, i.e. your desktop (the eGPU assuming only the rendering tasks). This might be too demanding for your modest iGPU.
During my tests, I observed performance drops of about 40-50%. So, yeah, it's quite significant. The difference between gaming in windowed mode or in full screen mode on Desktops is negligible in comparison...
For this reason I would strongly advice to NOT use the window drag method with any MacBook (equipped with an on-board dGPU or not)...