Late 2016 MBP with Dell U2718Q 4K Monitor - How to stop lag?

[kryptogram]

I've done a good bit of searching and tried a number of recommendations from folks in different threads but am having no luck. Also noticed almost every thread is with an older MBP, so not sure if Thunderbolt/USBC could be a problem here.

I just picked up the Dell U2718Q monitor to use as an external display (mirror mode) with my 2016 13" Macbook Pro (non-touchbar) that has two thunderbolt 3 ports. For what it's worth the machine has 512GB SSD and 16GB RAM with the Intel Iris Graphics 540 1536 MB and is the 2.4 GHz Intel Core i7. I am on Sierra (10.12.6).

When using the external monitor it's noticeably laggy and really unusable in pretty much every application. Sometimes it's moving the mouse, opening a window, etc. My machine is not under heavy load from any other application for RAM or CPU usage and I am talking about just using a browser, word process, or a terminal window that seems to cause problems. This is both at the recommended natively supported (way too high of resolution (non-scaled) settings and even if I use scaled and start lowering it to any of the 5 settings for lower resolution.

I'll add that it's exceptionally and particularly laggy anytime the cursor crosses some kind of window or button that requires it to change to a cursor or hand etc. So if I move the cursor over the top part of a browser window with open tabs -- you think I have 128MB of RAM with how it moves.

The first time I set it up I connected with a Belkin USBC->HDMI adapter and plugged in via HDMI. Now I just picked up a cable that does USBC->DisplayPort. I am not seeing any real difference between the two connection methods. It just sucks no matter what. Kind of at a loss of what I can do here or how anyone could use this thing as an external monitor. As far as I know there's no specific drivers I can grab to try and improve this.

Anyone have this monitor with my same laptop and able to use it without issues? Anyone see anything obviously wrong with my setup or have any other recommendations that might do the trick? Seems kind of nuts I can't use an external monitor. TIA.

 

[ixxx69]

I've done a good bit of searching and tried a number of recommendations from folks in different threads but am having no luck. Also noticed almost every thread is with an older MBP, so not sure if Thunderbolt/USBC could be a problem here.

I just picked up the Dell U2718Q monitor to use as an external display (mirror mode) with my 2016 13" Macbook Pro (non-touchbar) that has two thunderbolt 3 ports. For what it's worth the machine has 512GB SSD and 16GB RAM with the Intel Iris Graphics 540 1536 MB and is the 2.4 GHz Intel Core i7. I am on Sierra (10.12.6).

When using the external monitor it's noticeably laggy and really unusable in pretty much every application. Sometimes it's moving the mouse, opening a window, etc. My machine is not under heavy load from any other application for RAM or CPU usage and I am talking about just using a browser, word process, or a terminal window that seems to cause problems. This is both at the recommended natively supported (way too high of resolution (non-scaled) settings and even if I use scaled and start lowering it to any of the 5 settings for lower resolution.

I'll add that it's exceptionally and particularly laggy anytime the cursor crosses some kind of window or button that requires it to change to a cursor or hand etc. So if I move the cursor over the top part of a browser window with open tabs -- you think I have 128MB of RAM with how it moves.

The first time I set it up I connected with a Belkin USBC->HDMI adapter and plugged in via HDMI. Now I just picked up a cable that does USBC->DisplayPort. I am not seeing any real difference between the two connection methods. It just sucks no matter what. Kind of at a loss of what I can do here or how anyone could use this thing as an external monitor. As far as I know there's no specific drivers I can grab to try and improve this.

Anyone have this monitor with my same laptop and able to use it without issues? Anyone see anything obviously wrong with my setup or have any other recommendations that might do the trick? Seems kind of nuts I can't use an external monitor. TIA.

From your description, it sounds like you're suffering from more lag than just being stuck at 30Hz, but that would be the first thing to confirm if you haven't already - open up "System Information" app (or via "About this Mac...") and under Hardware > Graphics/Displays, select your video card and it should list the display connected to it and the resolution / refresh rate. If it indicates 30 Hz, that's likely the issue. If it indicates 60 Hz, then either there's an issue with your computer or the 540 just isn't powerful enough to make it as smooth as expected.

What scaled resolution do you have it set at? Have you tried different resolutions to see which one seems smoothest, i.e. scaled 1080p?