First of all, Avid Media Composer is meant to be installed by a system integrator. If you are deploying Media Composer for your team, be sure to have a specialist on your team, or get outside help.
To get an idea of the initial scope, have a look at these official recommendations. Don't be fooled by how old they are; they still apply:
Avid has very specific requirements for Media Composer to be used successfully. These requirements aren't dictated by PostLab but by Avid. Many teams simply install Media Composer, then stop there, thinking it's a simple app. That will lead to lots of avoidable trouble.
To make the most of your remote/hybrid/work-from-home workflow, we've compiled a list of tried-and-true optimizations. This list is essential and, thus, mandatory when implementing Avid, and PostLab for Media Composer.
A note to Team Owners:
We are not a system integrator. It is not our responsibility to make your Avid environment work.
99% of all incoming support issues are solved by implementing these requirements. As Team Owner, it is up to you to make sure each Team Member implements all the steps in this guide on their computer.
If you followed this guide, looked for your answers among the Questions, and still require assistance, Team Members can use the Request Support option in PostLab, which gives you a direct line to our support team.
For workflow issues that fall beyond the scope of PostLab support, Enterprise teams can request access to Professional Services.

1. Use a qualified combination of macOS and Media Composer

When Avid successfully tests a version of Media Composer on a specific version of macOS, Avid declares that combination qualified.
Use Avid's documentation to find the qualified combination of Media Composer and macOS that is best for you:
From Chris Bové, Online Community Manager and Customer Advocate, Avid Technology

2. Update macOS and Media Composer to the latest possible qualified combination

It's highly probable the latest version of Media Composer won't be qualified for the latest version of macOS. However, Media Composer may be qualified to run on a more updated version of macOS you're currently using.
When in doubt, ask your Team Owner, or confirm which combo is qualified for your Mac.
With rare exception, do not update Media Composer or macOS while working on a Project.

3. Connect to the network over Ethernet (Hard-wired, Cabled)

With all things cloud, including PostLab Drive, latency is the enemy. Wi-Fi typically has 100x times more latency than ethernet, so network performance will be poor when editing if you're not connected via Ethernet.

4. Store your Drive Cache on a super-fast local disk

Caches need fast drives. Store your Drive Cache on an internal SSD or NVMe, an external SSD or NVMe, or a RAID built for random IOPS performance. More info.
Although great for storing and playing back media, for caching RAID 0, 5, or 6 arrays typically don't work. If you use such a device for your media, don't use it for your Drive cache. Instead, use a dedicated SSD or NVMe, whether internal or external over Thunderbolt 3/4. You can use this for Drive and any other apps that let you define a location for its cache. Pro tip: Apple's internal SSDs are great for caching.

5. Eliminate All Performance Inhibitors on Your Mac or Local Area Network

If Media Composer isn't performing as expected on your local computer, here are some known performance inhibitors:
  1. 2.
    Your Mac's Energy Saver settings allow your Mac to sleep or for disks to spin down. Modify your Energy Saver settings to:
    1. 1.
      Computer Sleep: Never
    2. 2.
      Put hard disks to sleep when possible: DISABLED
  2. 3.
    Your Mac has a screen saver enabled.
  3. 5.
    Your computer is behind an active firewall, using an active antimalware/antivirus client, or is using a cloud-based security service, such as Crowdstrike.

6. Remove OpenIO_VirtIO.acf from Avid Media Composer.app‌

Using Blackmagic Design hardware for video playback? Skip this step.
Starting in Media Composer 7.0.4, Avid packaged this plug-in with Media Composer – OpenIO_VirtIO.acf. Media Composer's installer doesn't let you choose whether to install this or not, so take these steps to remove it manually:
  1. 1.
    Quit Media Composer.
  2. 2.
    In Finder, locate the Avid Media Composer application.
  3. 3.
    Control-Click on it, and select Show Package Contents.
  4. 4.
    Go to ../Contents/SharedSupport/AVX2_Plugins.
    • Note: depending on the version of Media Composer, this folder could be ../Contents/SharedSupport/AVX_Plugins.
  5. 5.
    Locate the OpenIO_VirtIO.acf file. Hold Option then drag a copy of it to your Desktop. (Your mouse pointer will change into a plus sign inside a green circle.)
  6. 6.
    Delete OpenIO_VirtIO.acf from the Avid Media Composer app package.
  7. 7.
    Relaunch Media Composer.
Removing OpenIO_VirtIO.acf results in a significant reduction of SFPlayConsumer::Execute TIMEOUT exceptions.

7. Disable Fast Scrub

  • MC 2021.x and newer: Settings > User > Timeline > Use Fast Scrub: DISABLED
  • ‌MC 2018.12.x: Project > Settings > Timeline > Use Fast Scrub: DISABLED
Disabling Fast Scrub results in a significant reduction of SFPlayConsumer::Execute TIMEOUT exceptions.

8. Adjust Settings > User > Audio

  • MC 2021.x and newer: Settings > User > Audio > ...
  • ‌MC 2018.12.x: Project > Settings > Audio > ...
    • Play Buffer Size in Samples: 1024 (could even be as low as 256)
    • Tool Buffer Size in Samples: 1024 (could even be as low as 256)
Adjusting Media Composer's Audio settings results in a significant reduction of SFPlayConsumer::Execute TIMEOUT exceptions.

9. Increase the Amount of Video Memory Used

Since Media Composer caches playback to RAM, ‌the more memory, the better. You can increase the amount of Media Composer uses to cache playback here:
  • ‌MC 2021.x and newer: Settings > Site > Media Cache > Video Memory
  • MC 2018.12.15: Settings > Media Cache > Video Memory
Then adjust these settings in Video Memory:
  • Desired Video Memory (GB): set to the desired amount (default: 2 GB)
  • Enable Playback Video Frame Cache: ENABLED
  • Enabled FX Editing Video Frame Cache: ENABLED
Since the amount of available RAM varies from computer to computer, we can't say how you should set Desired Video Memory. It's best to increase or decrease the amount of memory by GBs, then test for any improvement in Media Composer (e.g. playback, scrubbing, exporting, etc.)

Still having trouble?

You reviewed the Initial Workflow Checklist, enabled Remote Locking, double-checked you fulfilled all Requirements, and still no success? Check out answers to some common questions here.