FCPX lag while editing (playback, moving the playhead)

What is this media drive? A rotating HD, I presume.

You have to serve three streams at once, and apply those effects in real time.

My guess is that the drive could be the bottleneck.

A few things that may help:

1) Close the Angle Viewer. You can tap 1,2, or 3 to cut or switch to a particular angle.

2) Create proxy media for the clips in the multicam, and switch to proxy preferred.

3) Use a nice fast SSD

What are the complete specs of the media you’re working with?

Please post an EtreCheck report https://etrecheck.com giving the application Full Disk Access in Privacy & Security System Settings. Copy the report and use the Add Text button to paste the result into reply box. 

It’s still playing multiple streams simultaneously. You should try using proxies. You might also want to generate an EtreCheck report and post it here using the additional text button to see if there is anything else in the system slowing it down.

I completely agree with Tom.

In addition to the nasty things already mentioned, you have been upgrading in place for well over a decade.

You still have stuff from probably El Capitan era. Over time, these old things cease to work correctly in newer versions of the OS.

I recommend that you get your mac back to sanity, by doing a clean install.

It is not much less work than it used to be.

1) Full backup using Time Machine; if possible, a second backup 2) System Settings->General->Transfer or Reset->Erase All Content and Settings This will leave only the OS itself, and erase all system modifications as well as all accounts, so you did do the backup beforehand, right? 3) When asked, choose to migrate from "another mac, drive or Time Machine backup"; select the TM backup drive used in step 1 4) Select to migrate ONLY the user accounts (no applications, settings or other files - otherwise you'd just be back to where you started) 5) Enjoy a properly working mac. Gradually install the applications that you do need. Never install any "cleaners" or "antivirus".

[Loaded] com.google.GoogleUpdater.wake.system.plist (Google LLC - installed 2024-03-08)
    Command: /Library/Application Support/Google/GoogleUpdater/Current/GoogleUpdater.app/Contents/MacOS/GoogleUpdater --wake-all --enable-logging --vmodule=*/components/update_client/*=2,*/chrome/updater/*=2 --system

  [Not Loaded] com.google.keystone.daemon.plist (Not signed - installed 2023-12-07)
    <Empty>

  [Loaded] com.macpaw.CleanMyMac3.Agent.plist (MacPaw Inc. - installed 2021-08-12)
    Executable: /Library/PrivilegedHelperTools/com.macpaw.CleanMyMac3.Agent

Honestly I'd recommend a system wipe and reinstall as you're carrying a lot of baggage that has been migrated going back years over multiple systems.

Chrome is sucking your system down. You need to fully uninstall it together with the keystone launch daemons.

CleanMyMac has likely damaged your Mac, which would be another reason to clean install the OS. That's fairly simple on Apple Silicon. Do a complete backup of the data volume. Use System Settings to erase the system and them reinstall from startup options. During the initialization process migrate only the users, nothing else. Then reinstall the applications you need as you need them.

What’s the drive you’re using? What’s the frame resolution? That’s a huge amount of processing in video and audio effects for multiple streams of video. Do you have generate optimized media for multicam checked on in settings? You might want to trash the optimized files and use proxies instead.

How much RAM does your M1 have?

While it is fine for general use, 8GB may start to be a limitation when editing - remember, this does double duty as normal RAM as well as VRAM. If you have 16GB, you can disregard the previous remark.

Please also follow Tom's advice and post an Etrecheck report.

There may well be other issues impacting your performance.

I am not familiar with that application specifically.

It may fine, I don't know.

I prefer to take matters into my own hands, though.

For example, finding very large files is extremely easy using only the Finder: