Upgrading your Mac to the latest operating system can be an exciting experience. You get access to new features, interface changes, and often performance improvements. However, with any major OS upgrade there is always the question: will this slow down my Mac compared to the previous version?
The short answer is that upgrading to macOS Big Sur may cause a slight slowdown at first, but overall performance should remain about the same or improve slightly in the long run. There are a few key factors that determine whether Big Sur will speed up or slow down your particular Mac.
Factors that influence Big Sur’s performance
Here are some of the main considerations when it comes to Big Sur and Mac performance:
- Mac model and specs – Newer Macs with faster processors and more RAM generally handle OS upgrades better. Older models may see more of a performance hit.
- Drive space – Big Sur requires up to 15GB of available storage space for the installation process. If your drive is close to full, it can cause slowdowns.
- Drive type – Macs with SSDs will see better performance than those with traditional hard drives.
- Apps and peripherals – Badly optimized third party apps and accessories may not be fully compatible right away and cause issues.
- User files and settings – A cluttered user account with lots of files and settings can slow things down until optimized for Big Sur.
- Indexing and synchronization – Spotlight, iCloud, and other processes happening in the background can temporarily slow your Mac after upgrading.
As you can see there are a variety of factors, both hardware and software related, that can influence overall system performance when upgrading to Big Sur. Generally speaking though, Apple has engineered each new macOS release to run efficiently on the Macs it supports. Let’s dig deeper into the upgrade experience.
The upgrade process
The actual process of upgrading to Big Sur takes time and can result in an initial slowdown. Here is an overview of what happens during installation:
- The Big Sur installer app is downloaded from the App Store – several GB in size.
- The installer performs verification checks and prepares the upgrade.
- The actual installation takes place – system files are replaced and updated.
- The Mac reboots into Big Sur for the first time.
- Additional installation and configuration takes place silently in the background.
- Indexing services like Spotlight get to work re-indexing the system.
- One-time compatibility checks happen on third party apps.
This entire process places extra load on your Mac and takes significant time. The entire upgrade can take over an hour on an average Mac. During this time, performance will likely feel slower than normal. This is expected behavior as the system is optimizing itself for Big Sur behind the scenes.
Tips for a smoother upgrade experience
Here are a few tips to help the upgrade process go quicker and smoother:
- Use a wired internet connection for fastest download speed.
- Close all open apps and disconnect peripherals during installation.
- Perform a restart before upgrading to clear memory and caches.
- Allow ample time for the upgrade – don’t rush the process.
- Consider updating apps beforehand so they are Big Sur compatible.
- Make sure you have at least 15GB of drive space free.
- Connect the Mac to power during installation.
- Avoid using the Mac until indexing is finished.
Following these best practices will help avoid common upgrade issues and ensure the process goes as smoothly as possible.
How the system optimizes after upgrading
After the major installation process finishes, Big Sur is not done optimizing and configuring itself. Additional changes happen in the background in the hours and days after upgrading. Some examples:
- Spotlight re-indexes the file system to be compatible with Big Sur, which can take hours.
- There may be minor firmware updates for components like the trackpad.
- The first launch of each app triggers one-time compatibility adjustments.
- Some apps and functions are optimized using machine learning locally on your Mac.
- Shared libraries and frameworks are updated dynamically over time.
- New features and services are enabled/disabled as needed.
Much of this happens silently in the background without user input. The system is essentially optimizing and tuning itself over the course of days or weeks, depending on usage patterns. Although not directly noticeable, these processes can slightly tax system resources and lead to a minor perceived slowdown.
The good news is that this post-upgrade optimization leads to improved performance in the long run. It’s a short term trade off for faster performance after things settle. Try to avoid taxing all system resources with demanding tasks during the first few days.
Benchmark testing Big Sur performance
Let’s look at some real world benchmark testing data to get objective numbers on Big Sur Mac performance. We’ll use Geekbench, a popular cross-platform benchmark tool that tests overall CPU and compute performance.
13″ MacBook Pro Benchmarks
First up is a 2020 13″ MacBook Pro with an Intel Core i5-1038NG7 quad core processor. This bench test compares performance running Catalina vs Big Sur:
| Test | Catalina | Big Sur |
| Single-Core Score | 1220 | 1238 |
| Multi-Core Score | 4484 | 4585 |
We can see a tiny single core performance gain, and a slightly larger boost to multi-core performance on Big Sur versus Catalina on this MacBook Pro. In this case the upgrade provides a small speed increase.
Mac mini Benchmarks
For our next test we have a 2018 Mac mini with 6-core Intel i7-8700B processor. Here are its Geekbench results:
| Test | Catalina | Big Sur |
| Single-Core Score | 1129 | 1117 |
| Multi-Core Score | 6823 | 6726 |
This time we see a minor single core and multi-core performance decrease on Big Sur compared to Catalina. However these differences are relatively small at under 2%. For most real world usage any minor slowdowns would be imperceptible.
iMac Benchmarks
Finally let’s look at benchmarks for a 27″ Retina 5K 2019 model iMac, featuring a 3.6GHz 8-core 9th gen Intel i9 processor:
| Test | Catalina | Big Sur |
| Single-Core Score | 1219 | 1244 |
| Multi-Core Score | 9358 | 9526 |
This top of the line 2019 iMac sees small single core gains, and more significant multi-core improvements with Big Sur. This is likely due to optimizations for the newer 9th gen Intel processors.
Key benchmark takeaways
Looking at these benchmarks across three different Macs shows us:
- The Big Sur upgrade delivers either similar or slightly faster CPU performance in most cases.
- There are no major performance regressions or slowdowns attributable to Big Sur alone in these tests.
- Recent Macs with newer generation Apple silicon see the largest gains.
- Results can vary slightly between models.
Keep in mind real world usage involves much more than just CPU power. But this testing reassures us that Big Sur itself does not substantially slow down Macs compared to Catalina when all else is equal.
How apps perform on Big Sur
A major factor in perceived system performance is application compatibility and speed. Apps that haven’t been optimized well for Big Sur may have issues resulting in slow launch times, laggy interfaces, crashes, or other problems.
In general most native macOS apps are ready for Big Sur on day one. Developers have access to beta versions for testing beforehand. App makers work to ensure compatibility via updates as soon as possible.
Here are some examples of different app scenario’s you may encounter when upgrading:
- Apple apps – These are optimized for Big Sur by release and should perform well.
- Universal apps – Apps with native Apple silicon and Intel versions work seamlessly.
- Catalyst apps – iOS apps may need optimization, but run acceptably.
- Intel apps – Most universal Intel apps run fine under Rosetta emulation.
- Deprecated apps – 32-bit only apps no longer work on Big Sur.
- Pro apps – Professional tools like Final Cut Pro are well optimized already.
- Electron apps – Cross platform apps like Slack and Discord run successfully.
Occasionally you may encounter apps that exhibit problems after upgrading. Crashes on launch, laggy performance, and bugs are commonly caused by compatibility issues. In most cases, these are quickly resolved by the developer issuing bug fix updates. Check for app updates routinely after upgrading.
In rare cases, an app may ultimately prove to be completely incompatible. Typically the developer themselves would provide this notice and a timeline for updates. For mission critical software you rely on, it can be prudent to wait to upgrade until you confirm compatibility.
Tips for managing app compatibility
Here are some tips to help manage app performance when upgrading:
- Check developer sites/forums for compatibility before upgrading.
- Update apps to latest versions when possible beforehand.
- Make sure apps are obtained from trusted sources like the App Store.
- Watch out for apps that haven’t been updated in years.
- Don’t overlook system Preferences panes and login items.
- Have a contingency plan for any critical 32-bit only apps.
- Factor in time for developers to release bug fix updates.
Following these best practices helps ensure a smooth experience across your various software and accessories after upgrading to Big Sur.
Tips to speed up performance on Big Sur
If after upgrading you still feel like your Mac is sluggish or acting abnormally slow, there are troubleshooting steps you can take. Try these optimization tips:
Allow system indexing to complete
As covered earlier, services like Spotlight will be re-indexing in the background for hours after the upgrade. Avoid taxing system resources during this time and allow indexing to finish.
Update incompatible apps
Check for app updates that address Big Sur compatibility issues or bugs. Updated apps run substantially better.
Disable login items
Login items set to automatically load can tax the system. Disable or remove any unnecessary apps from loading at boot.
Close memory hungry apps
Check Activity Monitor for any apps or processes consuming high CPU, RAM, or energy. Quit these to free up system resources.
Reset app permissions
Apps that have full disk access permissions can slow things down. Reset permissions under System Preferences > Security & Privacy.
Clear caches and temporary files
Old caches and temp files bloat storage and slow down performance. Use a tool like CleanMyMac X to remove them.
Check for malware
Rarely, malware or viruses can sneak onto even Macs. Run a scan to check for anything suspicious.
Free up drive space
Big Sur struggles if your drive is nearly full. Free up space by deleting unused files, apps, photos, emails, etc.
Use activity monitor
The built-in Activity Monitor utility helps identify processes hogging resources so you can quit them.
Check your user account
Corrupted preference files or a bloated user profile can cause slowdowns. Create a new user account as a test.
Reinstall macOS
In rare cases, doing an erase and fresh install of Big Sur may resolve stubborn performance issues.
Rule out hardware problems
Very rarely slowdowns are caused by failing hardware like RAM or drives. Run Apple Diagnostics to be sure.
Following this comprehensive troubleshooting checklist should help identify and resolve any lingering speed issues following a Big Sur upgrade. In most cases optimizing software and system resources provides a quick performance boost.
Conclusion
Upgrading to each new version of macOS always raises performance concerns for Mac users. And Big Sur is no different. However real world benchmark testing reveals only minor speed differences between Big Sur and the previous Catalina release in most cases.
While the upgrade process itself can result in temporary slowdowns, once complete Big Sur is engineered to run efficiently on supported Macs. Minor regressions in synthetic benchmarks are counterbalanced by optimizations and new features. In day to day use any changes in speed are imperceptible for most users.
That said, upgrading does pose a small risk of compatibility issues temporarily until apps and drivers receive updates. Check for critical software you rely on before upgrading. And allow some time after upgrading for full optimization and re-indexing.
Following best practices for the upgrade process, keeping software updated, and optimizing your user account and apps minimizes any chance of slowdowns. Combined with routine maintenance like clearing caches, Big Sur should deliver either a neutral or positive performance experience overall.