FCPX 10.4.9 update and suddenly unusably slow

I see that you have Color Finale. It is up to date?

Any other plugins, particularly any from CoreMelt? There is a known issue where CoreMelt plugins need to be uninstalled and reinstalled to work in 10.4.9.

Also, do you need to have torrent software running?

I see also that you have NTFS software from Paragon. Is it up to date?

Third party antivirus are worse than useless on a mac. They can hinder performance severely (especially in professional applications). They conflict with the built-in system security.

And they offer no protection against the common malware, which are Trojans, which are of the social engineering variety: they require the user to install stuff, often by posing as something else. When the user allows the install of a contaminated piece of software, there is nothing the antivirus can do about it.

Below is an important text that all mac users should read and understand, and it explains it much better than I possibly could:

"Effective defenses against malware and other threats":

https://discussions.apple.com/docs/DOC-8841

You have a LOT of old software accumulated over several years (and, presumably, several macs).

Just look at this excerpt from the Etrecheck report:

    /System/Library/Extensions
        AvidDX.kext (5.9.0 - SDK 10.6)
        Soundflower.kext (1.5.2)
        DigidesignFireWireAudio.kext (9.0)
        DigiDal.kext (9.0.5 - SDK 10.5)
        DigidesignMbox2Boot.kext (10.3.5.211 - SDK 10.6)
        DigidesignMbox2.kext (10.3.9.12 - SDK 10.7)
        DigidesignElevenRack.kext (Digidesign Eleven Rack 1.0.1)
        MXOAudioDriver.kext (2.1.9.0004)
        PACESupportFamily.kext (5.9.1 - SDK 10.6)
        SonnetSATA.kext (2.2.9)

Startup Items:
    GenArtsRLMLicenseServer Path: /Library/StartupItems/GenArtsRLMLicenseServer 
    DigidesignLoader Path: /Library/StartupItems/DigidesignLoader 
    ProTecVb Path: /Library/StartupItems/ProTecVb 

Startup Items have been discouraged for a long time; they probably do not even work.

Installing any non-Apple extensions under /System/Library has been forbidden ever since Yosemite, at least.

So you have to have had them installed for that long.

Old system extensions will cause all sorts of problems.

For an example which is close to my heart: the great and very useful SoundFlower, only the most recent version 2.0b2 works in Mojave and Catalina; you have 1.5.2 (and, of course, any such extension should be in /Library/Extensions instead)

This is why many of us recommend doing a clean install when doing an upgrade.

You are due for one.

In a separate message I will post detailed instructions for how to perform a clean install.

Of course you need to BACKUP first!

One tip, early on, was to disengage Background Render. The spinning beachball is largely a symptom of a conflict between foreground (active work) and background use of processing. There is something screwy going on, possibly with Apple being so keen to get everything into 64bit, but what do I know? Live is a constant workaround needing a higher level of concentration that's a bit less human.

Can you give the specs of the computer and the media?

Start by resetting your preferences. Hold Opt-Cmd as you launch the application.

Did you uninstall and reinstall the updated versions of those plugins?

10-bit H265 is terrible to work with, both because of the bit depth and the codec that needs a lot of processing. You should probably just work with proxies.

For every 5 mins my FCPX bring the whole OS (2017 iMac) to about 10 seconds of crawling speed.

Holding cmd+option to reset preferences fix it for a couple of days, then the problem reappear.

I have ColorFinale and CoreMelt installed, but not using them lately.

Uninstall Avast completely.

My suggestion would be to do a Carbon Copy or SuperDuper clone of the drive and then erase the system drive and do a clean install. Migrate the users and reinstall only the applications you need.

First, switch off background rendering.

What’s the computer? What drives are you using? what’s the media? How much free space do you have?

I had the same problem. I switched off background rendering and that has done the trick for me.

A week on....

I bought a 4Tb drive, did a fresh Mojave OS base and then got FCP X 10.4.10, with the help of Macworld pages. I do admire the Apple way of keeping the interface, in all this, upbeat and 'all under control' though in fact I had to do a LOT of under the bonnet (hood) stuff, 2 days worth and counting. So, is it worth it? I'd prefer my working life of 3 weeks ago but the bright shining future of FCP X is, worth sticking with. I can report: not much of the advice on here was accurate (trashing of Chrome and flags from the EtreCheck - caused more problems with legacy audio and video acquisitions - I am using a lot of archive movie). Loads of stuff is now contained within the App itself (try 'show contents'). My LUTBuddy is a thing of the past, and the built-in Custom LUT works well).

Sure, if you have a backup copy somewhere. Maybe on Time Machine? You can have both versions on the system at the same time.

If your working library has been updated and you don’t have a backup that’s a bit more of a problem.