macOS Big Sur launch appears to cause temporary slowdown in even non-Big Sur Macs

Mac users today began experiencing unexpected issues that included apps taking minutes to launch, stuttering and non-responsiveness throughout macOS, and other problems. The issues seemed to begin close to the time when Apple began rolling out the new version of macOS, Big Sur-but it affected users of other versions of macOS, like Catalina and Mojave.

Other Apple services faced slowdowns, outages, and odd behavior, too, including Apple Pay, Messages, and even Apple TV devices.

It didn't take long for some Mac users to note that trustd-a macOS process responsible for checking with Apple's servers to confirm that an app is notarized-was attempting to contact a host named oscp.apple.com but failing repeatedly. This resulted in systemwide slowdowns as apps attempted to launch, among other things.

What a brave new world - some server goes down, and you can't use your applications anymore.