Mac Slowing Down on Zoom Calls? Here's How to Fix It

You join a Zoom call and within five minutes the fans are screaming, your battery is bleeding 1% per minute, and switching to Chrome to look something up takes an embarrassing five seconds. By call number three of the day, even basic typing is laggy.

Zoom is genuinely heavy software. It does real-time video encode/decode, noise suppression, virtual backgrounds, screen sharing, and chat — sometimes all at once. But on a healthy modern Mac it shouldn’t bring the whole system to a crawl. If yours does, here’s why and what to do about it.

What Zoom is actually doing during a call

When you’re in a Zoom meeting, your Mac is:

1. Capturing video from the camera (continuous)
2. Capturing audio from the mic (continuous)
3. Running noise suppression on incoming and outgoing audio
4. Running background blur or virtual background (if enabled)
5. Encoding your video to send up
6. Decoding video from every other participant
7. Compositing all those video tiles
8. Running chat, polls, breakout rooms, and the like

The encoder/decoder is the heaviest part by far. On Apple Silicon Macs there’s hardware acceleration for it. On older Intel Macs it’s all CPU, and that’s where heat and lag come from.

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Test 1: Check Activity Monitor mid-call

Open Activity Monitor before your next call, switch to the CPU tab, and sort by % CPU. Then join Zoom and watch.

What you should see:

• zoom.us — the main process. 30-80% on Intel, much less on Apple Silicon
• Zoom Helper processes — there are several
• VTEncoderXPCService — system video encoder (Apple Silicon only when working correctly)
• AudioComponentRegistrar — audio plugins

If any single Zoom process is over 200% sustained, something’s wrong. Possible causes covered below.

Fix 1: Turn off virtual background

Background blur and virtual backgrounds are computationally expensive. The blur effect specifically uses ML models that run continuously. On older Macs, this is often the reason Zoom is slow.

To turn it off mid-call:

1. Click the up-arrow next to the video button
2. Choose Choose Virtual Background
3. Select “None”

If you need to look professional, a clean wall is faster than a virtual background. Or use the “Standard” video filter at most.

Fix 2: Disable HD video

HD video doubles the encoding work compared to standard quality. Most Zoom call participants don’t need to see your face in HD.

Zoom → Settings → Video → uncheck “HD”

The image quality difference is barely noticeable in a Zoom tile that’s 320 pixels wide. The performance difference is significant.

Fix 3: Stop “Enhance my appearance”

Zoom has a soft-focus skin smoothing filter labeled “Touch up my appearance.” It’s another ML model running continuously on your video.

Zoom → Settings → Video → uncheck “Touch up my appearance”

You’ll look exactly the same. Promise.

Fix 4: Check Zoom for extra plugins and integrations

Some companies install Zoom plugins for Outlook, Slack, calendar integrations, or note-taking AI. Each one runs as a background process while Zoom is open.

Check:

• Activity Monitor → search for “zoom” — count the processes
• Zoom → Settings → General → look for unfamiliar integrations
• /Library/Audio/Plug-Ins/HAL/ — for audio plugins (Krisp, third-party noise suppressors)

If a third-party noise suppressor like Krisp is running, and Zoom’s built-in noise suppression is on, you’re doing the same work twice. Pick one.

Fix 5: Quit other heavy apps before joining

Zoom needs maybe 1-2 GB of RAM and a chunk of CPU. If your Mac is already loaded up with Chrome (30 tabs), Slack, Spotify, Photoshop, and a Docker container, Zoom is fighting for resources before it even starts.

The realistic minimum I’d quit before a Zoom call:

• Any browser tab playing video (YouTube, autoplay news sites)
• Spotify (or pause playback)
• Photo/video editors not actively in use
• Adobe Creative Cloud apps in the background
• Docker, if it’s running

You don’t have to quit Slack — but consider muting notifications so the popup animations don’t fight Zoom for compositor time.

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Fix 6: Check thermal status

If your Mac is throttling thermally, every app feels slow during a Zoom call, not just Zoom. Symptoms:

• Fans audibly maxed out
• Bottom of MacBook is hot to the touch
• Even text fields lag
• Mouse cursor stutters

Things to try in the moment:

• Move to a cooler room or get the Mac off a soft surface
• Lift the back of the laptop slightly for airflow (a couple of pencils work)
• Close every tab and app you’re not using
• Disable virtual background and HD (fixes 1 and 2)

Long term: clean dust out of the vents (Air can with the Mac powered off), make sure background processes aren’t burning CPU when you’re not on calls.

Fix 7: Use the browser version for short calls

Zoom in a browser uses less CPU than the native app for many use cases — especially if you’re just listening, not presenting. The browser version uses less heavyweight WebRTC code paths.

Test this: pick a low-stakes call. Join via the “Join from your browser” link instead of opening the app. If your Mac feels markedly cooler/quieter, browser-Zoom might be your default for routine calls.

The native app is better for screen sharing, larger meetings, and webinars. Use it when you need it.

Fix 8: Update Zoom (and macOS)

Zoom releases updates frequently, and several have specifically improved Mac performance. Old versions of Zoom on new versions of macOS are a known bad combination.

Zoom → check for updates. Update macOS too if you’ve been putting it off.

Fix 9: Reset audio routing

Sometimes Zoom audio gets stuck in a bad state where it’s polling the mic and speakers excessively. CPU goes up, audio quality goes down. The fix is restarting Zoom — and sometimes also the system audio:

1. Quit Zoom
2. Open Activity Monitor and force-quit coreaudiod
3. Reopen Zoom

This is a niche fix but solves a specific class of “Zoom keeps using a lot of CPU even with my video off” issue.

Fix 10: Reduce video tiles you display

If you’re in a 30-person Zoom call with everyone on camera, your Mac is decoding 30 video streams simultaneously. Switching to “Speaker view” cuts that to one or two.

• View → Speaker
• Or hide non-video participants: View → Hide non-video participants

Massive CPU savings on big calls.

What’s actually under the hood: the cleanup angle

A Mac that’s clean and unburdened handles Zoom much better than a Mac that’s running a year of accumulated background processes, login items, and cache files. The biggest categories of cleanup that affect Zoom performance:

• Login items — apps that auto-launch and run silently. Check System Settings → General → Login Items.
• LaunchAgents in ~/Library/LaunchAgents/ and /Library/LaunchAgents/ — auto-running services
• Old cache files that bloat memory and starve Zoom of RAM
• Leftover preferences from apps you uninstalled (these can still spawn helper processes)

Manual cleanup of all of this takes hours. Sweep finds it in one scan and shows you what each item is and what it does before you remove it. The speed boost feature also frees inactive RAM right before a call — clean slate before joining. Notarized by Apple, free download.

Don’t restart — cleanSweep clears the buildup that’s actually slowing your Mac. No reboot needed. Free for macOS →

A pre-meeting checklist

Five minutes before any important call:

1. Quit Chrome/Safari (or close down to one tab)
2. Quit Spotify, Music, anything playing media
3. Plug in to power if on battery
4. Close Slack notifications (or set DND)
5. Close any photo/video editor in the background
6. Click the camera preview before joining to make sure it works

That’s the prep that separates a smooth call from a heat-throttled mess.

When it’s the network, not the Mac

If Zoom feels laggy because video keeps freezing or audio cuts out, that’s not a Mac performance issue — that’s network. Check:

• Other devices on the same Wi-Fi: are they also laggy?
• Speed test (fast.com): under 10 Mbps up/down struggles for HD video
• Ethernet adapter: rules out Wi-Fi entirely

A Mac performance issue and a network issue feel different. Mac issue: fans roar, everything is laggy, Zoom video stays smooth. Network issue: Mac feels normal, Zoom video freezes.

Final note on Apple Silicon vs Intel

If you’re on an Intel Mac (especially pre-2019) and Zoom is brutal, that’s largely the hardware. M1 and later have hardware video acceleration that makes Zoom dramatically lighter. The cleanup advice above still helps, but won’t fully close the gap. If Zoom is your daily driver and you’re on a 2017 MacBook Pro, an M2 Mac mini would change your life.