Significant System & Mouse lag after high sierra install

Do you have any peripherals attached to your Mac? In that case, remove everything and try with a new start.

If the issue is still there, try to reboot in safe mode Use safe mode to isolate issues with your Mac - Apple Support and see the behaviour. In case still issue, then reset the NVRAM how described in this article: How to reset NVRAM on your Mac - Apple Support and if still there, well give a try with this tool: https://etrecheck.com/ and post here the result.

UPDATE:

Apple Support did some troubleshooting with me and ended up concluding that High Sierra was having some compatibility problems with 3rd party video adapters. I had 2 USB-C to HDMI adapters from Anker. Apple sent me one of their adapters but before I received it the problem went away with the last High Sierra update.

I have the same problem with my Magic Mouse 2/ Magic Trackpad 2. In my case, turn off the wifi can fix the problem. This is incense that using a MacBook Pro without wifi.

It can be that something is going wrong with the update and resetting the SMC and/or the NVRAM usually helps, so if resetting the parameters and the plugin the devices solve the problem is fine. If not, just contact the support: Official Apple Support

The answer from getangar, below, has instructions for resetting the NVRAM and that fixed my problem with a sticky mouse pointer.

My system is a Mac Mini with 16 Gigs memory running High Sierra, the Apple wireless keyboard and mouse.

Similar issue here with a 2017 iMac. Did you find a way to keep you monitor connected? Our computer is a presentation computer that NEEDS to be connected to 2 monitors. I get mouse lag/freezing in 2 separate scenarios:

1. The set up that worked before updating to High Sierra was 2 USB-C to HDMI adapters feeding 2 external monitors. 1 is a TV the other is HDMI to a DVI adapter connecting to a switcher. Disconnecting the HDMI to DVI connection removes the mouse lag
2. I was able to get a lag free system after update by bypassing the switcher and running HDMI straight to a projector BUT the lag reappears if the projector and/or TV are OFF.

Thanks,

Try this:

SystemPreferences->Network (unlock)->Advanced->TCP/IP tab:

set "Configure IPv6" to: Local-Link only, click OK

Click Apply.

Close the Network page.

I am adding this post/reply to note that, while the issue cleared up for me temporarily by resetting NVRAM, it returned with a vengence. I'm running High Sierra on my Mac Mini, Late 2012 (maybe that's the issue-older Apple whatevers get left in the dust) and decided to ask how to roll back the update. If I followed the procedure described, I'd have to set aside two or three days to get through it and set up all my apps. Until Apple fixes this issue, I've moved work I'm doing for client to a Linux box. Really prefer my Mac Mini, yet I've got work to do and deadlines to meet. As a one man shop, I cannot spend hours tinkering for solutions.

I do recommend you reset NVRAM as well as PRAM and see if this fixes the problem for you. Perhaps, if you've a newer Mac Mini, iMac or any flavor MacBook this will be the fix. Or, perhaps the newer models are not having this issue.

Open Bluetooth and delete the existing pairing with the mouse.

Restart the mac (to empty some caches).

Connect the magic mouse and pair it again.

I just rolled back to El Capitan. I don’t see the point in upgrading to an OS that runs slower and breaks things. The instability and performance degradation outweighs the features in high Sierra.

Agree. It now takes several attempts (clicking and waiving the mouse around) to log on. There are numerous problems like this (iPhoto crashing out during editing being one) with the High Sierra upgrade - I wish I'd not bothered with it. Apple don't like to admit there is anything wrong. I hope these issues will be fixed in the near future.

Feel a little silly that I had forgotten the arrow keys. Thanks.

Oops, had to wait to post this since an Apple alert informed me my post limit was reached and that I needed to wait a bit before it will add my response.

Really? I get emails from Apple notifying me about replies and encouraging a response. The original post generated quite a number of replies, yet apparently Apple isn't so keen on my sitting down when I have time and responding to all that took the time to add to the discussion. Boo, hiss.

Perhaps they will be fixed; it's likely. I want to know why Apple updates have become quite unreliable. When Jobs was around this did not happen, and, if it did, some folks were out looking for new employers. Hope, I assert, is a cousin of something highly addictive, perhaps on a level like nicotine, for example.