Glad that helped, @iamkashifnadeem.
For the Mailpit issue, it could be that you have an old Intel version left on disk from the previous install. You can try these steps as mentioned above:
Hi everyone! Try deleting it and downloading it again.
I use macOS Sequoia 15.3.1. It took me so long to update to the latest version of Local, and I really regretted it. After that, it became so stressful to do anything — the program was still incredibly slow, even after I spent so much time zipping, saving, and deleting projects in vain.
But then I finally read a comment from someone who deleted the program and installed it again — and it solved the problem. It worked for me too!
Thank you for sharing an update @sarahmatos! Glad to hear you got things working 
Like many of you here I have been having this same issue (Apple M1 Pro on Sequoia 15.4.1). Switching between sites in the UI, and about any other action, would take 8 to 12 seconds.
Deleting the app (not uninstalling) and downloading the ‘Apple Silicon MacOS’ version resolved that for the most part.
When opening Local again for the first time I did get this error (just the one time):
Uh-oh! Unable to swap services.
Error: EEXIST: file already exists, mkdir ‘/Users/[---------]/Development/localwp/conf/nginx’
When opening sites it prompted to re-install PHP and also Mailpit.
The only issue I have no is that it keeps warning me that Mailpit is not installed, that it will install it when site starts, over and over again.
Followed steps (also from here) to delete MailPit and that worked.
cd ~/Library/Application Support/Local/lightning-services
Delete the folder named mailpit-1.12.1+0
Local is running quickly. All my sites/data still present, and Mailpit works just fine.
Thanks everyone.
Thank you for sharing the update @donohoe!
Logged in to let you know this worked for me. Thank you whoisandywhite!
Thank you all for your patience and communication with us here! We’re going to close out this topic for now. For any new users who are coming here, to recap:
If you’re experiencing slowness in your Local app on MacOS after updating, check to see if you’re using the Intel Version and if so manually update to Apple Silicon as shown here.
If you’re also getting errors related to MailPit not starting, you might need to manually reconfigure it as shown here.
For any new questions, concerns or issue feel free to spin up a new post!
Just noting for anyone reading that this was fixed in Local 9.2.6, it is no longer required.
https://localwp.com/releases/9.2.6/
Also, 9.2.6 now warns Apple Silicon users if they’re on the Intel version of Local by mistake, and prompts them to download the Apple Silicon build.
.