Q: Apple TV 4th Gen Lag using Airplay between MacBook Pro and Apple TV

That will be due to the network

If on wifi try Ethernet

Make sure no other activity is occuring (other streaming, web browsing, network backups etc)

Test on another network

Well if Airplay is working fine between your iPhone/iPad and your ATV, then I would have to say that:

1. Your WiFi is fine

2. it points to an issue with your MBP with your Wifi

Johnny

Airplay is over the local network so Internet speed isn't relevant. Other devices working doesn't rule out a network issue and more resources are needed from the network when mirroring a Mac. Best to troubleshoot as above

As I said above

If on wifi try Ethernet

Make sure no other activity is occuring (other streaming, web browsing, network backups etc)

Test on another network

You can also see a report of the network by going to istumbler (signal strength, noise, nearby networks)

This was a well documented problem with the older Apple TV's that was never addressed conclusively.   Tons of people could get great streaming quality with their iphones over airplay, but the macbook pro would not stream smooth.  Even when streaming the exact same content.  If you read some of those old posts there's lots of things you can try.  Some seem hit and miss on if they actually help.   I tried everything with my macbook pro (late 2013) and old apple tv to get streaming smooth, nothing ever worked.   It could be your connection speed, or network settings that's always possible.   You can try forcing 2.4 or 5 ghz depending on your environment, kicking other devices off the network, etc. 

I can say that I recently bought the new Apple TV and it streams great with my macbook pro.   Which tells me that it was never a problem with my macbook pro or it's internet settings, it was a problem with the old Apple TV.    Nothing changed in the loop but the Apple TV,  same macbook pro, same router, same wireless connection, same locations, etc.  

No, there were a select group that posted about issues but the issue will lie with the network just like there are for the current model and versions prior. Another device working isn't going to rule that out and taking it to another network or to Apple would show that it often works in another environment.

Yes, it will come down to things like changing channels/frequency band on the router. other activity and load on network, distance from router, router settings etc

If nothing in the system changes aside the replacement of the problem device, it's either the device, or how it interacted with the network/laptop.   Not the network itself, network settings, or the laptop.   At best it's a failure of the automatic handshaking between the incoming data from the Macbook and the apple TV or some interference between them, which since the Apple TV is the only device having an issue, again it falls to the Apple TV as the problem.

Nothing else changed, same network, same # of devices, same laptop, same router, same locations, same internet connection speed.    All that changed was swapping out an older Apple TV for the new generation.    If it was a network bandwidth issue, or laptop network setting that was creating the problem, changing the device that the laptop was streaming to would NOT fix the issue, it would still not be able to stream fast enough to work smoothly to any device.   I'd see the same problem streaming to the TV directly, or to a Fire Stick, etc. and I don't.   It also would mean that no device would stream at a similar quality level to the Apple TV.  

I'm not saying that in the original poster's case that trying different network settings etc. might not fix his particular problem, but once all of those options are exhausted you start to look at hardware.  It's well documented many people have had problems specifically streaming from a Macbook's to Apple TV's, when the ONLY problem is the Apple TV itself, streaming from the macbook to other devices worked fine, and so did streaming from other sources (iphone etc.) to the Apple TV. 

At the end of the day I don't really care what the underlying technical cause is.  If I have 20 devices on my network, none of which have problems with bandwidth, streaming, etc. and the Apple TV is the only problem child, and replacing it fixes the problems, that's all I need to know.

Network issues can come at at any time, and of course a network issue can impact a single device. Saying there isn't a network issue because it's working on other devices is making an assumprion. If it's a matter of the interaction, then that falls to the network and not the device. Again, a select group has posted about such issues for each version of the device. It has also worked for the majority for each and when those users have done the proper troubleshooting the network issues can be resolved. Also, as stated taking it to another environment would show that it works just fine.

Has anyone got the solution to this problem? I'm also facing this issue of lag on my ATV 4th gen when mirroring from my MBP.

Lag will be due to the network, mirroring requires a lot of resources. What troubleshooting have you done?

Hi. I think computer users sometimes don't realize how mirroring or extending their display differs from the basic AirPlay they use when streaming via an iOS device. The following is a brief description of the two video AirPlay modes, and why you always want to use basic AirPlay if possible.

Video AirPlay works in two modes. Basic AirPlay just sends the video URL to Apple TV which then streams it directly. This usually works best since there's no double transmission. You're using basic AirPlay when the video player on your device goes black and says "This video is playing on Apple TV". On a computer, you do this using the AirPlay icon that appears in the controls of a screen video player object, in the browser or other app. On iPad or iPhone, use the AirPlay controls on the right hand pane of the iOS 10 Control Center, or the AirPlay icon in the video player.

The other mode is Mirroring, which generates an H.264 video stream from the device frame buffer and transmits it over WiFi to Apple TV. This video compression inherently limits resolution, and may have trouble with fast motion. When you put the iPad or iPhone video player into full screen mode, mirroring automatically switches to basic AirPlay, and it seems to be impossible to prevent that from happening. On iPad or iPhone, mirroring is on the left hand pane of the iOS 10 Control Center. On a Mac computer, you access this mode from the AirPlay icon in the main menu bar. It lets you mirror the main display, or create a new display, extending the desktop. But remember that the data sent to the Apple TV is always being converted to a live video stream. Actual display frame buffer pixels are not transmitted, as they are to a directly connected monitor.