Sidecar lag in iOS 15

After ANY iOS/iPadOS upgrade/update, you should ALWAYS perform a simple hard reset of your Apple mobile device.

For iPad models with a Home button, do a simple hard reset of your iPad by holding down both the Home and sleep/wake/power button simultaneously until your iPad goes to black and restarts with Apple logo, then release the buttons.

OR

For much newer design iPad models, without a Home button, try the new simple hard reset procedure for the new 2018/2020/2021 iPad Pros, 2020 iPad Air 4 and 2021 iPad Mini 6 models.

1. Press and release the volume up button.

2. Then immediately press and release the volume down button.

3. Then, press and hold the single sleep/wake/power button You will see the Slide to Power off button, but keep on holding down the power button until you see the Apple logo, then let it go.

Once you have performed all the steps, wait for a few seconds and your 2018 iPad Pro will boot up completely to the iPad Pro’s Lock screen.

Best of Luck to You!

Connect them together with a cord. I have a Macbook Pro 2020 M1and I just used the charger to connect the macbook to the iPad (its usb-c). Works like a charm. For now there doesn't seem to be a fix for the lag when using sidecar wirelessly. That will probably be fixed in future updates

I get the same thing with my MacBook and iPadPro. It's particularly bad if connected wirelessly. Over USB, it's not so bad. It definitely appears to be a memory leak. Open Activity Monitor and watch WindowServer slowly grow and grow as you use SideCar over time. If you don't use Sidecar, it doesn't grow. If you do use Sidecar it just grows indefinitely and eventually your machine grinds to a halt. I'm using sidecar at the moment, and it's OK so far - WindowServer only at 1.05GB (!) but in a couple of days I will have to reboot the machine again, once it becomes unusable.

I have the same problem, but I got a wired but working solution on my side. My device set is a late-2016 MBP 13 with MacOS Big Sur 11.4, and an iPad Pro 11-inch 2019 with iPadOS 15.1.

I have used sidecar since this function was available at the very beginning, but had the very-laggy sidecar experience since I upgraded to iPadOS 15 from 14.xx. I have searched online but found no other solution other than using cable connection between the devices (way smoother). However, I just found that after using cable sidecar for only a few seconds, if I unplug the cable, the screen will say "unable to connect to iPad ...". Then when I reconnect them using wireless sidecar, the lag was gone somehow. I wouldn't say super smooth as cable connection, but the obvious lag was just gone and became at least usable for me. (I use iPad to paint in Photoshop.)

Hope this helps.

I just paired a 2018 iPad Pro with my M1 MacBook Air, and it was VERY laggy. I turned off and back on the iPad and switched both the laptop and the iPad to my "normal" wireless at home, instead of my 5G WiFi band and it's working as expected now; no lag.

I have this problem too, but the lag was fixed when I'm using it via wired connection. So I suggest to others to do the same if you haven't tried using wired connection.

I've been having the same issues. I've been using my Ipad Pro 2018 Ver as a second monitor using Sidecar, since I purchased my Macbook Pro M1 back in February of 2021. It has worked without any lagging until now. Ever since I upgraded to IOS 15 it has connection issues. I keep getting "The session will resume automatically when the connection improves" the problem is the connection never improves and it makes sidecar completely unusable as well.

I have same problem on MBA M1 running bigSur 11.6 and iPad Pro M1 11'' on IOS15.0.2, supper laggy when sidecar especially with mouse movement, several reconnection, several toggling handoff/bluetooth, helplessly, not sure what kind of ecosystem compatibility now of apple on the same SoC...big disappointment