Message app slow and lags on Big Sur

I found this and it worked for me.

Sonia Huelsenbeck says

APRIL 3, 2019 AT 9:53 PM

After trying all the suggested fixes, I contacted Apple. They had me do the following and it worked:

Sign out of Messages on the MacBook. We can do that by opening Messages, then going to the top left corner of the screen and click messages -> iMessages. We should be able to sign out from there .

Up next we’ll go on the iPhone to Settings -> Messages, turn off iMessage, restart the iPhone, then turn iMessage back on.

Go back on the MacBook and get signed back into the Messages app. 

Go on the iPhone to Settings -> Messages -> Text Message Forwarding. We should be able to flip a switch for the Mac to allow us to send SMS and MMS messages from the MacBook, and hopefully sort out the last of it.

Enter the code that pops up on your screen.

If you're having issues with laggy typing check the font the app is using. I apparently had a different font set in Messages that was no longer found and it was filling up the console with errors about not being able to find it or the size. 

I went into Messages preferences and changed the "Text Size" at the bottom to "Default" and restarted Messages. No more errors and typing was back to normal! It bugged the **** out of me for months!

Sign OUT of all devices. Reboot all devices. Sign back on with your iPhone, and AFTER you are signed back on, THEN sign on with each other device, ONE AT A TIME. You should be good to go after that. Consider your iPhone as the MASTER device for Messages, and the other devices as SLAVES. The slowness is coming from SYNC'ing.

The only fix that works for me, and that seems to be temporary, is the one stated earlier to log out of all Message apps on my Mac, iPad, and iPhone, then log back in first with the iPhone and then with the iPad and iPhone afterward. That makes the lag go away for a week or two and then the sync issue slowly seems to rear its ugly head and I have to repeat the procedure. Clearly a software bug. Apple??

I had the same problem but only on one Mac. I have Big Sur installed on a MacBook Air, a MacBook Pro, a Mini, and an iMac, and it was only running slow on the Mini. It would also freeze and needed to be forced to quit. It's a 2014 i7 3 GHz 16 GB RAM Intel Iris 1536 MB. Everything else works fine, so I checked all settings and found one different. I set it the same as the other Macs, and Messages works absolutely fine now. That one setting was in Accessibility > Display > Cursor > Cursor Size. It was set on the 4th (middle) size. I reduced it to the smallest size even though the other Macs are on the second setting. As I said, works perfectly now.

It is something to do with SYNCing. The more devices you have to Sync, the worse it is. Sometimes one device will fail to sync at all. I think it is similar to the phrase, "Get Your Ducks In A Row," where the server tries to make sure that all the devices are updated to the same hierarchy. I hope Apple fixes it. I started seeing this problem when I went to Big Sur. Before that, everything seemed to work okay. Since I signed out on all devices, then back on with just the iPhone, before attempting to sync my iPad and iMac, I haven't had the problem. It sure drove me crazy at first though! Glad this worked for you.

73, de KØUNX, Jim, in Jefferson County Colorado

I had the same problem. Sometimes seconds between pressing a key in iMessage and the character appearing. I went into System Preferences -> Accessibility and made sure I had the lag time for a key press set to minimum. It seems to have fixed the problem ... for now, at least.

I have Wha'sApp

This is very annoying indeed. The way I handle it is by re booting on "Safe" mode for a little while and then go back to the normal reboot and it takes care of the issue but it comes back a few days later.

Rebooting into safe mode and rebooting again was one of the first things I tried. There's a reason why we reboot first, but changing my Accessibility settings appears to have been a permanent fix. Messages hasn't frozen on me again. Hope that helps.

OK I had to do 1 more step.... after all of the above, I had to turn off the iPhone one more time and when it was turned back on, the switch to enable text messages suddenly appeared in the IOS Setup app under messages...

all good now

Fiddling with text size seemed to bring some immediate relief. Whether or not it stays is another question. So far, other fixes haven't worked or were only temporary.

This problem is so bad I've considered downgrading to Catalina. Really frustrating.

I finally got a chance to work with Apple Support on this issue and they escalated my case up since I spoke to Support about this in September. We are trying to figure out if there is 3rd Party app that is causing this issue. If you have this issue, please reply if you have any of the following 3rd party applications to try to figure out if there is a common denominator:

Spark

Fantastical

Microsoft Office Apps (Excel, Word, Powerpoint, etc.)

WhatsApp (wish Messages worked as well)

PDF Expert

EZCCs

Ulysses

iMazing Profile Editor (or other apps by DigiDNA)

Kiwi for Gmail

Speedtest

Mactracker

OneDrive

Dropbox

Speedtest

There are enough people having a problem with this lag that we may be able to narrow this down by app.

Reboot only fixes it temporarily. I did that and after few days it came back. I even upgraded fusion drive to a super fast SSD 2T in my 2017 iMac 27 as I thought this new Mac OS Big Sur requires faster disk speeds but the problem is still there. Messages are laggy as I was working on 15 years old machine.

I agree. The fix works, but the problem comes back. It appears to be a sync problem across platforms. With a Mini, an iMac, a MacBook Air, an iPad Pro, and iPhone 11Max next to each other a message doesn’t appear on all screens for several minutes at times. Sometimes it works extremely well. I go through the suggested fix, and the results are immediately obvious, but then it comes back within a day or two.