Golden gate update was a mistake.

For your MacBook Air 13-inch (M1) running macOS 27.0, I would work through this using some of Apple’s own troubleshooting guidance rather than assume that Golden Gate is the cause.

When an app refuses to quit, first try Command-Q or the app’s Quit command. If that does nothing, press Option-Command-Esc and choose Force Quit. 

If the app still will not close, Apple recommends restarting the Mac. Apple Support — How to force an app to quit on Mac

There is one macOS 27 feature that is particularly relevant to what you described. 

Apple says that some apps can continue running in the background after you quit them, and macOS 27 indicates this in the Dock. 

Background activity can also affect Mac performance. 

You can review this under System Settings >> General >> Login Items & Extensions >> Background App Activity. 

This is different from an app that has actually become unresponsive. Apple Support — If an app continues running in the background after you quit it

Since you are also seeing frequent system-wide lag, open Activity Monitor while the slowdown is happening.

Apple provides it to examine CPU, memory, energy, disk, and network activity. 

Also check System Settings >> General >> Storage, since Apple identifies insufficient available storage as one possible reason a Mac may run slowly. Apple Activity Monitor User Guide Apple Support — If your Mac runs slowly

If the problem continues, try Safe Mode. On your M1 Mac, shut it down, Do Not use Restart, hold the power button until the startup options appear, select your startup disk, hold Shift, and choose Continue in Safe Mode. Apple says Safe Mode can help determine whether software that loads during startup is involved.

It is also worth reviewing System Settings >> General >> Login Items & Extensions to see what is allowed to open at login or run in the background. Apple Support — Open items automatically when you log in

If the problem persists, Apple provides Disk Utility for checking and repairing the startup disk when appropriate. Apple Support — If your Mac runs slowly

When an application becomes unresponsive, Activity Monitor can create a Spindump report, and System Diagnostics can collect additional information that may be useful to Apple Support. Apple Activity Monitor — Run system diagnostics

If the problems remain after these software checks, Apple Diagnostics can test the Mac for possible hardware problems. Apple Support — Use Apple Diagnostics to test your Mac

I would handle the Siri problem separately by checking the internet connection, Siri settings, and microphone operation rather than assuming Siri is causing the overall slowdown. Apple Support — If Siri on Mac doesn’t work as expected

Finally, check System Settings >> General >> Software Update and make sure your apps are up to date. 

Apple recommends checking for updates when an app repeatedly stops responding. Apple Support — If an app on your Mac stops responding, closes unexpectedly or won’t open

This gives you a practical Apple-supported path through the issues you described—apps not quitting, apps becoming stuck, persistent lag, background activity in macOS 27, storage and disk checks, startup software, Siri, and possible hardware problems—without assuming in advance what is causing them.

slesage wrote:

Thanks for the reply. As I wrote, the problem in Sequoia was fixed before I upgraded. I cannot run the app you suggested as the problem is the WIFI, bluetooth and access to network are all disabled. I have very few third party apps. I had a VPN that I uninstalled in Sequoia.

Thankfully my old Macbook running on Monterey works fine... and so does my iPad.

I would like to know where I can prevent other apps to run on startup. That includes CleanMyMac...

If you have CleanMyMac installed, then uninstall it by following the developer's instructions. This particular app is notorious for causing all sorts of problems and sometimes referred to here on the forums as "BrickMyMac". Simply deleting the app is not going to remove the tendrils it has within macOS.

As Barney-15E already said, I'd recommend:

Backup via Time Machine or Carbon Copy Cloner or Super Duper.

Disconnect all peripherals that are not needed in the next steps.

System Settings > General > Transfer or Reset > Erase All Content and Settings...

Test.

Restore ONLY user data files via Migration Assistant (or manually -- keep the backup for a few weeks until you are certain you haven't missed anything from ~/Library folder etc).

Test.

Carefully re-install ONLY mission critical essential 3rd party apps one-by-one and test how they behave.

...necessary or not, but as a "hobby" I always do something like that before any OS upgrade and I have NEVER experienced major glitches in ANY Mac OS upgrade since 1990.

...rest of the family happily just upgrades on top of old cruft and go on without problems. But sometimes for some folks there is old stuff that intervenes and produces hard to diagnose issues.

Note that this is Apple Support Communities, not Apple Support. “We” are users like you and have no power to implement any suggestions. Apple employees are generally precluded from even reading these forums, with the exception of moderators who only monitor for compliance with the T&C.

To have Apple consider your feedback, submit it here:

Feedback - macOS - Apple

If you are having specific issues, you are welcome to post them as topics here and most likely other users will try to help you.

There are always bugs in a new major macOS upgrade. Most are eventually resolved by point updates, but some point updates create new bugs. I typically update my personal Mac, iPad and iPhone immediately, and I hold off on updating my work Mac until the x.1 or x.2 update. 

Personally, I've never experienced significant issues with macOS or iOS upgrades. Minor annoyances yes, but nothing that has meaningfully impacted my workflows. For example, once in a while on macOS 27.0.1 the screensaver setting will change itself from my usual selection (an album in my Photos Library) to the macOS Golden Gate screensaver. I change it back, it sticks for a day or two then switches. A minor annoyance, not meaningful to me. I reported the bug to Apple, as usual. At some point, it will be fixed.

Consider that the macOS 27 (Golden Gate) developer beta was released on June 8, 2026, followed by the public beta on July 13, 2026, before the full software officially launched on September 14, 2026. That's three months of developer testing and two months of public testing, both across several iterative beta versions. And of course, plenty of testing internally before Apple released the first developer beta.

In general, MAJOR issues are going to be found and fixed before the full release. What is left that impacts the general public mainly falls into three categories:

• Identified bugs that were not of sufficient impact/priority to fix before full release
• New, unidentified bugs that are found by users
• Issues caused by incompatible software/extensions installed by the user on a prior version of macOS

By far, the majority of issues fall into that last category. 

Some people ask about rolling back to Tahoe. Reverting to an older major version of macOS is not simple. You need to boot into Recovery OS, erase your internal drive, then install the older macOS, then restore from a backup made prior to the recently applied upgrade. Even then, the firmware on the Mac may have been updated, meaning potential conflicts and a possible need for DFU mode and a Configurator revive/restore, which would need to be done via another Mac connected to yours. If that sounds complicated and risky, then you're assessing the situation correctly.

Just to add to the advised offered from colleague @HWTech

Any Third Party Applications that will interfere with the normal operation of the OS,  is an invitation for disaster. 

Certain Applications maybe available on the Apple Apps Store - this only means the Developer is prepared to pay Apple a percentage on each sale. 

What the Application may do to the computer is up to the User to check this out before purchase

Any of the below should be removed as per Developers Instructions 

Disk Cleaner 

CleanMyMac , aka “ BrickMyMac “

There are about 11, 500 examples of those who have experienced what CMM BrickMyMac can and will do Even After removing the application as per the Developers' Instructions

There are two schools of thought when dealing with CleanMyMac aka “ BrickMyMac “

The steps in #1 below is predicated on the Offending  Application has been Removed as per the Developers Specific Instruction 

# 1 Some Contributors suggest restarting in Recovery Mode and choosing to Reinstall the Operating System over the existing installation. 

This may or may not replace elements of the  Home Folder ( User Account )  and replace any corrupted or removed elements and make things right.

#2 - Then there are Other Contributors ( like myself ) would suggest  from this link Use Disk Utility to erase a Mac with Apple silicon.

Use the Erase All Content and Settings feature to quickly and securely erase all settings, data, and apps, while maintaining the operating system currently installed.

Thereafter to start from scratch and install all Required Applications directly from the Apple Apps Store or Directly from the Developer leasing CMM out of this.

If going this route - I suggest Not using Startup Assist to migrate things back as this will probably Re-Introduce the existing  issue at the time TM Backup was made 

Apple is not here so they will not see your comments..

You can provide feedback to Apple here:

Product Feedback - Apple

slesage wrote:

I had problems with Sequoia losing internet access on sleep mode. Forgetting network seemed to fix it. Someone suggested I upgrade to Golden Gate. Big mistake because the forgetting network fix doesn’t work anymore. This is on iMac M1.

How can I go back to the old system?

FYI, upgrading to a new major OS version rarely fixes existing issues. Installing a minor OS update patch is a different story though.

Always figure out any existing issues prior to upgrading to a new major OS version.

Most problems are usually due to issues with third party installed software. Or people trying random fixes found online or suggested by AI.

You can try running the third party app EtreCheck and posting the complete report here so we can examine it for possible clues.

How to use the Add Text Feature When Posting an EtreCheck Report - Apple Community

Hope they will fix it all. i really hope.

I do not experience any of those problems on an M4 mini nor M2 MacBook Pro. Your problems are caused by something else installed on your system that will likely never get fixed by Apple since it isn’t caused by their software.

I see you noted that you have installed BrickMyMac. In that case, you’re only hope of restoring functionality is to Erase all Content and Settings, and then migrate from your time machine back up only your data, no apps or settings. Reinstall any other apps from source

I had problems with Sequoia losing internet access on sleep mode. Forgetting network seemed to fix it. Someone suggested I upgrade to Golden Gate. Big mistake because the forgetting network fix doesn’t work anymore. This is on iMac M1.

How can I go back to the old system?

Thanks for the reply. As I wrote, the problem in Sequoia was fixed before I upgraded. I cannot run the app you suggested as the problem is the WIFI, bluetooth and access to network are all disabled. I have very few third party apps. I had a VPN that I uninstalled in Sequoia.

Thankfully my old Macbook running on Monterey works fine... and so does my iPad.

I would like to know where I can prevent other apps to run on startup. That includes CleanMyMac...

I could not use the Erase all contents and settings as it was inactive without any network connection. So I used the disk utility and erased the Macintosh HD. It was a no-win because I needed an Ethernet connection to reinstall an operating system… It meant rearranging the furniture to move the modem to connect. And I was happy to go back to Tahoe, which is what they offered. It still did not recognize my Bluetooth keyboard and trackpad.

I connected my TimeMachine - it looked like nothing was happening so I restarted without it. Most of you will not know what I’m talking about when I say that I had to enter username and password using AZERTY French mapped keyboard on QWERTY French Canada physical keyboard, but the challenge is interesting…

So with all that the problem still not solved. I fiddled with all the other tricks I had tried before, and Installing and forgetting the network seemed to work.

My joy was short lived, because the connection died again after inactivity.

slesage wrote:

I could not use the Erase all contents and settings as it was inactive without any network connection. So I used the disk utility and erased the Macintosh HD. It was a no-win because I needed an Ethernet connection to reinstall an operating system… It meant rearranging the furniture to move the modem to connect.

Why didn't you connect via Wi-Fi?

And I was happy to go back to Tahoe, which is what they offered.

Offered where or via what workflow? If you were previously using Golden Gate, at least Erase all contents and settings should keep on GG, same with Recovery although sometimes it might not be in sync with the latest macOS. Or did you download Tahoe and installed it?

I had to enter username and password using AZERTY French mapped keyboard on QWERTY French Canada physical keyboard

Were you not offered to set your location and keyboard layout during the setup? Or did you perhaps use a 3rd party external keyboard?

I connected my TimeMachine - it looked like nothing was happening so I restarted without it.

I can't comment on that because I use Carbon Copy Cloner. But that was actually good so no potentially corrupt settings were restored to the newly installed system.

So with all that the problem still not solved. I fiddled with all the other tricks I had tried before, and Installing and forgetting the network seemed to work. My joy was short lived, because the connection died again after inactivity.

Your original post didn't mention these connection problems. Maybe try to reboot the router or try another router if the connection problem is also with Tahoe. Bummer. I wonder why you are still having problems. Maybe a hardware issue.

slesage wrote:

I could not use the Erase all contents and settings as it was inactive without any network connection. So I used the disk utility and erased the Macintosh HD. It was a no-win because I needed an Ethernet connection to reinstall an operating system… It meant rearranging the furniture to move the modem to connect.

Why didn't you connect via Wi-Fi?

Because that was the problem. It said WIFI deactivated and trying to click it on did not work.

And I was happy to go back to Tahoe, which is what they offered.

Offered where or via what workflow? If you were previously using Golden Gate, at least Erase all contents and settings should keep on GG, same with Recovery although sometimes it might not be in sync with the latest macOS. Or did you download Tahoe and installed it?

When I used the option to erase with the disk utility, the ONLY option available in the absence of a WIFI connection, when the system turned back on, it showed installing Tahoe as an option.

I had to enter username and password using AZERTY French mapped keyboard on QWERTY French Canada physical keyboard

Were you not offered to set your location and keyboard layout during the setup? Or did you perhaps use a 3rd party external keyboard?

Again, when coming back from the erase disk utility, the options were more limited, with only English or French. My Bluetooth keyboard is the one I purchased with my iMac in 2021. Now I of course have all the options, since I can use the option under Settings (Réglages)

I connected my TimeMachine - it looked like nothing was happening so I restarted without it.

I can't comment on that because I use Carbon Copy Cloner. But that was actually good so no potentially corrupt settings were restored to the newly installed system.

So with all that the problem still not solved. I fiddled with all the other tricks I had tried before, and Installing and forgetting the network seemed to work. My joy was short lived, because the connection died again after inactivity.

Your original post didn't mention these connection problems. Maybe try to reboot the router or try another router if the connection problem is also with Tahoe. Bummer. I wonder why you are still having problems. Maybe a hardware issue.

A day later, after a few restarts, the system seems to be stable under Tahoe. I tried to do a setup with my iPad, but it did not find it. I will therefore reinstall any app from the suppliers. Thankfully my personal files are either on an external drive that I have been sharing with my MacBook Air, or in the Cloud.

No definitely not hardware. I feel there is still a ghost in there, linked to security/permissions for Bluetooth and WIFI.

Thanks for the support!

slesage wrote: I had to enter username and password using AZERTY French mapped keyboard on QWERTY French Canada physical keyboard

Normally there should be an icon in the top right corner where you can select the input source that matches your hardware keyboard, Canadian-CSA in your case.

Yes Tom « normally », that is with a fully functional operating system, not during recovery after having erased it with the disk utility.