Final Cut Pro 12.3 not responding, high fault count

I agree with Ian - this looks like there could be some corrupted file.

A badly formed movie file could cause this.

As it is, and if you haven't already, you will probably have to Force Quit the application: press Command-Option-Escape, select Final Cut Pro and click Force Quit.

Then start FCP while holding down Command and Option and click "Delete Custom Settings".

Try again. If the problem reappears, it is likely that either the movie file itself or the project is corrupted.

Define, specifically, what "fairly large video file" means, please?

Any 3rd party apps being used on those clips?

And yeah, delte all render files, turn off background rendering, delete pref files, all as suggested already. We'll go from there/

Your CPU usage isn't that high, a single core or maybe two or three is nothing to worry about. And fault counts mean nothing to anyone besides machine language engineers. That number has to get really high before anyone needs to look at it. Ignore it. And that's not a lot of virtual memory, which is always being used for specific tasks that lend themselves to virtual memory.

My friendly AI provides this explanation:-

In macOS Activity Monitor, "faults" measure page faults, which occur when a process needs data that isn't currently loaded in physical RAM. Seeing a high fault count for launchd (the master macOS process) is completely normal and not usually an indication that the system is broken. 

Breaking Down Faults

• Soft Faults: A referenced memory page is already in physical RAM but is unmapped. These are generally harmless and happen constantly.
• Hard Faults (Page Ins): The needed memory page was swapped out to your SSD and must be retrieved.
• The Bottom Line: A high number of faults means your Mac is heavily utilizing virtual memory. If you also have high "Memory Pressure" or "Swap Used," it means your Mac doesn't have enough RAM for the processes you are running.

It is possible your project or some clip in it is corrupt so create a new Library and Project with different media to test it.

How much free space have you got on your drive . . . it should be at least 20% or you can expect problems.

Restart your Mac.

Delete the preferences . . . hold down Command and Option as you launch FCP and click "Delete" in the window that opens.

What app has produced those results you show?

Got it! He's double-clicked on launchd in Activity Monitor.

No need to worry about Faults . . . look at mine and my M4 mini is behaving perfectly!

Looks like they are just a normal part of the macOS which gets bigger the longer you are since booting.

More AI Bumf:-

In launchd, a fault refers to an error where the macOS background manager is repeatedly trying to launch a crashing program or a corrupted script. Because launchd is the parent of all processes, these faults usually manifest as a resource drain (high CPU or energy) originating from launchd and its logging system (logd).

How to Diagnose and Fix the Faults

1. Find the culprit causing the fault

Activity Monitor alone won't show you the specific fault; you need to look at the system logs.

• Open the Console app (found in Applications > Utilities).
• Click Log Reports or All Messages and search for launchd or logd.
• Look for repeating messages like "process respawning too quickly" or "could not find active service for lookup" to see which third-party application, login item, or script is failing.

2. Delete or Disable the Corrupt Launch Agent/Daemon

Once you know the name of the app or service crashing, you can stop the loop by removing its .plist file from your system.

• Check these directories for the corrupted application or plugin:
  • ~/Library/LaunchAgents/
  • /Library/LaunchAgents/
  • /Library/LaunchDaemons/ 
• Look for files with the faulty app's name, drag them to the trash, and restart your Mac. 

3. Use a third-party management tool (Optional)

If you are uncomfortable navigating system directories, a dedicated utility like LaunchControl provides an intuitive, graphical interface to identify, view, and disable rogue system agents safely. 

Have you any idea where the OP's screenshot is from as I don't recognise it as Activity Monitor?

Just noticed that his free space is OK.