QLab 5GeneralA Computer Prepares – QLab 5 Edition

A Computer Prepares – QLab 5 Edition

What follows here is a list of the programs or processes which we recommend disabling and instructions for doing so, as well as some other recommended practices. This section presupposes a basic understanding of macOS and at least a passing familiarity with the Terminal, which can be found in Applications → Utilities.

The directions here are accurate for Macs using macOS Big Sur (11) and macOS Monterey (12).

Click here to download our “Prep and Restore” tutorial workspace (current version: September 2022). The workspace contains two Script cues. The first one executes all the prep steps below, not including the video-specific ones or the ones which have to be done using the mouse. The other Script cue reverses these steps. Because it is a tutorial workspace, it does not require a QLab license to work despite using Script cues.

A note about sudo

sudo is a Unix command which is short for “superuser do.” It allows you to run a command in the Terminal with “superuser” privilege. In normal human terms, this means that using sudo allows you to run a command that you ordinarily could not, usually because that command could have serious consequences, and it would be a security risk to not require some kind of extra confirmation. There have also been reports of sudo being successfully used to obtain a sandwich.

sudo can only be used by an administrator account. If you only have one account on your Mac, it’s almost certainly an administrator account. If someone else set up your Mac, ask them about it. It is really very useful to run QLab using an administrator account and we recommend it if at all possible.

The Terminal commands below all use sudo, which means that the first time you use them in a new Terminal window, you’ll be asked to enter your password. This is not nefarious; this is macOS making sure that you are indeed proactively choosing to do this thing, and also that you are a person and not a sneaky script or bot trying to pull a fast one. None of the commands below transmit anything to or receive anything from outside your Mac.

The Basics

First, make sure that your copy of QLab resides in the Applications folder on your Mac. Most of the time, Macs are very permissive about where things can be stored, but you can occasionally encounter problems which you would not otherwise encounter when running a program that is not kept inside the Applications folder.

Next, make sure that there are not multiple copies of QLab on your Mac, or if there are (for example if you deliberately want to use QLab 5 sometimes and QLab 4 sometimes,) ensure that only one of them is named “QLab” and the other is named something else like “QLab 4” or “Old QLab” or “QLab Just For The Holiday Show.”

System Software

There are a number of programs, processes, and tasks that your Mac runs either periodically or all the time in the background. Many of these programs are essential, but many are not and disabling them will increase the total percentage of your computer’s resources which are available to QLab.

Disable Spotlight

Spotlight is Apple’s name for the macOS search tool. What makes the tool work so well, and so quickly, is a clever program which periodically updates an index of all the files on every disk or drive connected to your Mac. This periodic updating can be fairly intensive, and can temporarily prevent QLab from getting access to data, which can cause late cues or stuttering playback.

Using System Preferences

Open System Preferences → Spotlight, click on the Privacy tab, and add every disk or drive that’s connected to your Mac to the list. You can do that by dragging and dropping the disk or drive’s icon from the Desktop into the list, or by using the + button at the bottom.

To restore Spotlight’s default behavior, remove all disks or drives from the Privacy tab list.

Using the Terminal

Open a Terminal window, type or paste in this command, and then press enter:

sudo mdutil -a -i off

mdutil, short for “metadata utility”, is the program that handles Spotlight configuration. -a means you want to apply this command to all disks and drives. -i means you want to turn indexing on or off, and off means turn it off.

To restore Spotlight’s default behavior, use this command:

sudo mdutil -a -i on

Prevent Sleep

Obviously we don’t want the computer to go to sleep during the show, nor do we want the screen to be turned off.

Using System Preferences

If you’re using a portable Mac such as a MacBook, MacBook Air, or MacBook Pro, open System Preferences → Battery. On the left side are buttons for “Battery” and “Power Adapter”. Choose “Battery” and then:

  • Under the label “Turn display off after,” drag the slider all the way to the right.
  • Uncheck the box labeled “Put hard disks to sleep when possible.”1

Now choose “Power Adapter” and then:

  • Under the label “Turn display off after,” drag the slider all the way to the right.
  • Check the box labeled “Prevent computer from sleeping automatically when the display is off”
  • Uncheck the box labeled “Put hard disks to sleep when possible.”1

Finally choose “Schedule.” None of these settings matter directly to QLab, but it’s good to make sure that your computer is not set to sleep or shut down during your performance.

If you’re using a desktop Mac such as a Mac Mini, iMac, Mac Studio, or Mac Pro, open System Preferences → Energy Saver and then:

  • Under the label “Turn display off after,” drag the slider all the way to the right.
  • Check the box labeled “Prevent computer from sleeping automatically when the display is off”
  • Uncheck the box labeled “Put hard disks to sleep when possible.”1

Using the Terminal

Open a Terminal window, type or paste in this command, and then press enter:

sudo pmset -a displaysleep 0 disksleep 0 sleep 0

pmset, short for “power management settings”, is the program that handles power management configuration. -a means you want to apply this command to all power supply situations (i.e. both while on battery and while plugged in, for laptops). The 0 following each keyword disables that form of sleeping.

This command often displays a little informational warning after it’s run, which you can ignore.

To enable sleep using the Terminal, use this command:

sudo pmset -a displaysleep {x} disksleep {y} sleep {z}

Replace {x}, {y}, and {z} with times measured in seconds. For example, sleep 600 will set your Mac to go to sleep after ten minutes (six hundred seconds) of inactivity.

Disable the Screen Saver

A screen saver is an inconvenience for any Mac running QLab, and a fairly substantial problem for a Mac running video.

To display the screen saver, open System Preferences → Displays & Screen Saver, click Screen Saver and uncheck the box labeled “Show screen saver”

Unfortunately, the ability to adjust screen saver settings using the Terminal does not work as of macOS Big Sur. It’s not clear if that was a choice by Apple, or a mistake. It can still be done via AppleScript, though:

tell application "System Events" to tell screen saver preferences
    set delay interval to 0
end tell

Disable Automatic Time Machine Backups

Backups are wonderful. You should back up everything as often as possible. But on a computer used for your show, backups should only be done manually. Time Machine, much like Spotlight, uses indexing and background processes which can take hold of the disk at inopportune moments.

Using System Preferences

Open System Preferences → Time Machine and uncheck the box labeled “Back Up Automatically”.

To restore Time Machine’s default behavior, re-check that box.

Using the Terminal

Open a Terminal window, type or paste in this command, and then press enter:

sudo tmutil disable

tmutil, short for “time machine utility”, is the program which handles Time Machine configuration. Unlike its friends, it has very straightforward syntax.

To restore automatic backups, use this command:

sudo tmutil enable

Disable Software Update

You don’t want your computer trying to update software in the middle of a run; if everything works and an automatic update introduces a bug or problem or even variation, it can cause a lot of last-minute stress or even a cancelled performance.

To prevent your Mac from automatically installing software updates, open System Preferences → Software Update and uncheck the box labeled “Automatically keep my Mac up to date”. You’ll be asked to confirm this choice.

Unfortunately, the ability to adjust Software Update settings using the Terminal does not work as of macOS Big Sur. It’s not clear if that was a choice by Apple, or a mistake.

Prevent Notifications

The usefulness of the macOS notifications system can be debated, but it fortunately makes it very easy to disable all notifications at once, leaving your QLab operator in relative peace.

To prevent notifications, open System Preferences → Notifications and check the box to enable Do Not Disturb during a specific time period, then enter a range of time that covers your whole working day, or basically the whole day. You could, for example, turn on Do Not Disturb from 4:00 AM until 3:59 AM.

Disable Photos Processing and Cloud Services

Apple’s Photos app does a huge amount of background processing, include face and object detection. The only way to make sure that Photos doesn’t keep your Mac busy whenever it thinks the system is idle (that is, during standby right before a major cue), make sure the Mac isn’t connected to your iCloud photo library.

  1. Open Photos;
  2. Choose Preferences from the Photos menu;
  3. Click iCloud;
  4. Uncheck the box marked “iCloud Photos”.

Log Out of iCloud

Even when your Mac is offline, iCloud is surprisingly assertive about checking in with the iCloud servers in Apple’s data centers. Logging out of iCloud ensures that this check-in process doesn’t claim processor power when you need it.

Open System Preferences → iCloud and click “Sign Out” to sign out of iCloud.

Minimize Internet Accounts

Similarly, any accounts used to sync Mail, Contacts, and Calendars can potentially try to access the Internet and take up processing power while doing so, even while network access is disabled.

Open System Preferences → Internet Accounts, choose an account, and uncheck each service type that you can do without. Repeat for each account.

Limit Internet Access

Many individual applications, including QLab, have their own internal scheme to check for updates, but as discussed above we recommend not updating anything during the run of a show.

One of the simplest ways to guarantee that automatic software updates or any other network traffic won’t bother your show is to disconnect the show computer from the Internet. We absolutely do not require this, but it can be a very wise thing to do unless you need internet access on your show Mac for some specific reason.

If you use a network to connect your QLab computer to other hardware, and your show doesn’t require Internet access, make sure that network is a closed LAN (local area network) and has no path to the Internet.

Show Mode and Task Switching

By default, QLab does the following when your switch your workspace into Show Mode:

  • Prevents use of ⌘-Tab
  • Disables Mission Control and Exposé
  • Disables automatic Dock hiding
  • Prevents your computer from sleeping
  • Activates “latency critical” mode, which prevents QLab from getting deprioritized access to system resources.

If you want QLab to not do this when in Show Mode, choose QLab Preferences… from the QLab menu and uncheck the box marked Disable disruptive OS features in Show Mode.

If You’re Doing Video

If you’re using QLab for video, the following settings are also very important:

Disable Mirror Displays

Whenever you have more than one display connected to a Mac (including the built-in display on a laptop or iMac), you can either have the displays mirroring each other, showing the same thing, or turn off mirroring, which lets each display show its own image. That’s how you want it set for QLab, so that you can see QLab on your display, and the audience sees your cues on the other display or displays. To turn off display mirroring, open System Preferences → Displays and choose Arrangement. Then, uncheck the box labeled Mirror Displays.

Disable Displays have separate Spaces

Spaces is Apple’s name for virtual desktops. If you don’t know what this means, don’t worry about it; the main purpose of Spaces is irrelevant to QLab, but they have a side effect that is important for video users: if your displays are set to have separate spaces, the Menu bar also appears on all displays, which means it will be visible to your audience when no cues are playing through QLab.

To fix this, open System Preferences → Mission Control and uncheck the box labeled Displays have separate Spaces.

Disable separate Spaces using the Terminal

Open a Terminal window, type or paste in this command, and then press enter:

defaults write com.apple.spaces spans-displays -bool TRUE

To restore separate Spaces using the Terminal

defaults write com.apple.spaces spans-displays -bool FALSE

Important: you’ll need to log out, then back in again for this to take effect. This is true whether you use System Preference or the Terminal command to make the change.

Blackout the Desktop

When QLab is playing a Video cue, it places a black “backdrop” over any screen that is being used by that Video cue. When no video is playing, however, QLab does not display this backdrop. Therefore, in order to prevent your audience from seeing anything when no Video cue is playing, you’ll need to set the desktop background on your projector (or other audience-visible display) to black. You can do that in two ways. Either:

  1. Open System Preferences;
  2. Choose Desktop & Screen Saver;
  3. Choose Desktop;
  4. On your projector (or other display), choose “Solid Colors”;
  5. Click “Custom Color…“;
  6. Set the color to black.

Alternately, QLab provides a quick and easy way to do the same thing. Simply choose Black out desktop backgrounds from the Tools menu, and all desktop backgrounds will be set to black. You can later choose Restore saved desktop backgrounds, also from the Tools menu, to restore the desktop backgrounds you had previously.

Other Software

Other programs running in the background can interfere with QLab’s performance in two basic ways: first, they can use system resources like processing power and memory capacity which would otherwise be available to QLab. Second, they can engage in activity that conflicts with QLab’s activity, such as altering a file which QLab is expecting to remain unaltered.

The single biggest and simplest thing you can do to ensure good QLab performance is to avoid running other programs on the same Mac as QLab during your show, besides programs which are necessary for your show.

Some programs are more… shall we say assertive about their background behavior than others. For example, Ableton Live is a very processor-intensive program, but only when it’s running. Simply having Live installed on the same Mac as QLab isn’t a problem at all; if you’re not using Live, it has no real effect on your computer. Adobe Creative Cloud, on the other hand, has not one but several helper programs which run all the time to keep the Adobe apps updated, sync data, facilitate logging into the Adobe CC website, and so forth. These processes are designed to have minimal impact, but minimal is not the same as zero and when you’re trying to get the best possible performance out of a computer, every little bit helps.

The Upshot

Quit programs that aren’t necessary during show time, disable or uninstall background processes that run all the time, and learn about the background behavior of the programs you do use so that you’re aware of what they’re doing when you’re not actively using them.

Avoid installing these programs on any audience-facing QLab system:

  • Any Adobe Creative Cloud program
  • Google Chrome, Google Earth, and Google SketchUp
  • LogMeIn, AnyDesk, TeamViewer, or other remote screen sharing software
  • Backblaze or other whole-disk automatic backup software
  • Dropbox, Box, Google Drive, or other automatic cloud file sharing software
  • Vectorworks Cloud Services
  • Antivirus software of any kind

To be clear, none of this should be read as an indictment of any of these programs, per se2. Mac computers are used for many different things, and different configurations of software are appropriate for different environments. A setup that works perfectly for one environment might be abysmal for another environment. That doesn’t mean there’s a problem with that setup.

Squeezing Every Last Drop of Performance

Sometimes we don’t get the budget we hoped for. Sometimes we are stuck using a Mac that was donated by a board member’s uncle’s friend’s former roommate. Sometimes the scope of the design outgrows the Mac that was fast enough for the original plan. These things happen! When they do, sometimes we need to dig as deep as we can and look for every 0.01 percent of processing power and memory availability to get our shows running smoothly.

The following settings are not recommended in general because they have a truly minimal effect on the overall processing load of your Mac. But when you’re really down to it, these are things you can try when you really are looking for that 0.01 percent.

Avoid MP3 and MP4/AAC files

Playing MP3 and MP4/AAC files takes more processing power than playing AIFF, WAV, or CAF audio files.

Match sample rate and bit depth

Technically, all audio needs to match the sample rate and bit depth of the output device that it’s playing through. Core Audio does an amazing job of resampling audio on the fly with essentially no processing overhead, but not resampling on the fly takes even less processing overhead.

Match resolution

Scaling video cues takes processing power. Render your video files at the exact size you need them wherever possible.

Use native video outputs

Outputting video via Blackmagic devices, Syphon, and NDI takes more processing power than using native video outputs. A native video output is one which appears in System Preferences → Displays.

Clear the Desktop

Each icon on the Mac’s Desktop requires processing power to display, believe it or not. Get as many items off of the Desktop as you can.

Reduce Motion and Transparency

macOS uses lovely motion and transparency effects for aesthetic effect, both of which takes processing power. Open System Preferences → Accessibility, select Display, and check the boxes marked Reduce motion and Reduce transparency.


  1. If your Mac only has SSDs attached to it, this checkbox has no effect.

  2. A notable exception: all antivirus software for the Mac is bad, and you should never use it. macOS has built-in security processes which do a better job, cost nothing, don’t slow down your Mac, and don’t try to scare you about invisible and unlikely threats.

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