12 Fixes for macOS Catalina Slow Performance Issues

Apple‘s newest macOS release, Catalina, stirred up excitement with its impressive new features like Sidecar and Apple Arcade when it launched in October 2019. However, that excitement quickly turned to frustration for many Mac users who found their machines stuttering and stalling after making the upgrade. If you‘ve been battling slow performance since updating to Catalina, you‘re definitely not alone.

In this article, we‘ll take a deep dive into the most common causes of macOS Catalina slowness and the steps you can take to get your Mac back up to speed. We‘ll pay special attention to performance issues that crop up when using the Migration Assistant utility. With these expert tips and techniques, you‘ll be able to diagnose and resolve slowdowns and get back to enjoying everything Catalina has to offer.

Understanding Migration Assistant

First introduced way back in Mac OS X Leopard, Migration Assistant has long been the go-to tool for moving user accounts, applications, settings, and files from one Mac to another. Whether you‘re upgrading to a new Mac or doing a clean installation of macOS, Migration Assistant aims to make the transition as seamless as possible.

So how does it work? When you run Migration Assistant, it scans the source disk (your old Mac‘s drive or a Time Machine backup) and collects all the data associated with each user account. That includes everything in the user‘s home folder, like documents, photos, music, and preferences. It also rounds up system-wide settings, email accounts, contacts, calendar events, and compatible applications.

Migration Assistant then transfers all of that data to the target disk on your new Mac or your freshly installed macOS. The idea is that when the process finishes, you‘ll be greeted with a carbon copy of your previous setup—same accounts, same apps, same files, same settings. No manual reconfiguration required.

While Migration Assistant does succeed in creating a seamless transition much of the time, it‘s not immune to issues. As any Mac technician will tell you, Migration Assistant is often the culprit when a Mac starts experiencing slow performance after an upgrade, especially if the old system had problems to begin with.

Migration Assistant and Slow Catalina Performance

According to a 2019 survey by MacWorld, a staggering 35% of users reported a significant slowdown after upgrading to Catalina. Of those users, over half had used Migration Assistant to transfer their data from an older version of macOS. So what‘s going on here? Why does Migration Assistant sometimes lead to a sluggish Mac?

There are a few key factors at play:

1. Migrating Bloat: Over time, Macs accumulate a shocking amount of digital detritus—outdated caches, broken preferences, forgotten downloads, and other hard drive-clogging junk. When you use Migration Assistant to move your data wholesale, you‘re bringing all of that bloat along for the ride. Gigs of unnecessary files can bog down your shiny new Catalina installation right from the start.
2. Incompatible Apps: Catalina dropped support for older 32-bit applications, rendering them unusable on the new OS. Unfortunately, Migration Assistant doesn‘t always catch these incompatible apps. It may attempt to transfer a 32-bit program‘s files, only to have them cause slowdowns and errors on Catalina.
3. Corrupted Data: An app‘s preferences or license file can sometimes become corrupted, leading to slowness, freezes, or crashes. When Migration Assistant copies over an app with damaged settings or a compromised database, those problems persist on your new system.
4. Hardware Bottlenecks: Older Macs with spinning hard disk drives (HDD) tend to have an especially tough time with Migration Assistant, since the transfer process is limited by the source drive‘s read speed and the destination drive‘s write speed. Migrating from an HDD-equipped MacBook to a newer SSD-based model can take many hours, during which your system may be too bogged down to use productively.
5. Bugs and Glitches: Like any software, Migration Assistant itself is not immune to technical hiccups. Users have reported issues with the app stalling out mid-transfer, skipping files, or crashing altogether. These incidents are relatively rare but can lead to incomplete migrations and ensuing slowdowns.

To quantify the impact Migration Assistant can have on performance, consider this benchmark data from a 2019 MacWorld study:

Migration Method	Average Time to Complete	Average Read Speed	Average Write Speed
Migration Assistant	2 hours 10 minutes	35 MB/s	22 MB/s
Manual File Transfer	52 minutes	90 MB/s	85 MB/s

As you can see, using Migration Assistant to transfer data from an older Mac often takes significantly longer and occurs at much slower speeds than simply performing a manual file transfer. For large data migrations, this performance hit can be especially punishing.

Troubleshooting Slow Performance After Upgrading

So you‘ve made the leap to Catalina, either with or without Migration Assistant, and now you‘re staring at a beach ball of doom. Don‘t despair! There are several proven troubleshooting techniques that can help whip your Mac back into shape.

Free Up Disk Space

A nearly full hard drive is one of the most common causes of general slowness on a Mac. macOS needs a certain amount of available disk space to function optimally, and when your drive‘s capacity is stretched thin, performance suffers.

Click the Apple menu and select ‘About This Mac,‘ then navigate to the Storage tab. This handy overview shows you what‘s eating up space on your startup disk. Catalina has some built-in options for slimming down your disk, like storing files in iCloud and auto-removing watched iTunes media.

For even more cleaning power, fire up a dedicated app like CleanMyMac X or DaisyDisk. These utilities are pros at seeking out and eliminating hard-to-find junk that‘s clogging up your drive.

Reset NVRAM/PRAM and SMC

A Mac‘s NVRAM and PRAM are small chunks of memory that store data like startup disk selection, time zone, and speaker volume. Occasionally this data can become corrupted, causing wonky behavior.

To reset NVRAM/PRAM:

1. Fully shut down your Mac.
2. Press the power button, then immediately hold Option, Command, P, and R.
3. Keep holding until you hear the startup sound a second time, or see the Apple logo disappear and reappear.

The SMC is another important component that manages things like your Mac‘s power supply, battery, and fans. If you‘re experiencing sluggishness or your Mac feels abnormally hot, an SMC reset can often help. The exact steps vary by Mac model, but Apple provides a full SMC reset guide for all machines.

Identify Resource Hogs with Activity Monitor

Some performance slowdowns are caused by a single misbehaving app monopolizing your Mac‘s CPU or memory. You can sniff out these resource hogs using your Mac‘s built-in Activity Monitor tool.

Open Activity Monitor from the Utilities folder in Applications. Click the CPU button, then the % CPU column header to sort processes by processor usage. Keep an eye out for any unfamiliar apps or processes using an unusually large chunk of your CPU.

Next, click over to the Memory tab and sort by Memory usage. If you spot any apps gobbling up multiple gigabytes of RAM, that‘s a red flag. Try updating the app to the latest Catalina-optimized version. If it‘s still acting up, you may want to remove it entirely and look for an alternative.

Turn Off Visual Effects

Catalina‘s flashy graphical bells and whistles sure look great, but they can also put excess strain on older or lower-powered Macs. If you‘re experiencing choppy animations or interface lag, try turning off some of macOS‘s visual effects:

1. Open System Preferences and click Dock.
2. Uncheck the following boxes: Magnification, Animate opening applications, Automatically hide and show the Dock.
3. Click Minimize windows using and change Genie effect to Scale effect.

Next, click Accessibility, then Display. Check the box for Reduce motion. This disables animations when opening and closing windows and switching between desktops.

Finally, click on the Battery icon in your menu bar and select Low Power Mode to throttle your Mac‘s processors and squeeze out extra performance.

Dealing with Incompatible Apps and Missing Data

After upgrading to Catalina, you may find that some of your beloved apps simply refuse to launch. Catalina axed support for 32-bit apps, so if you‘re seeing a "This application is not optimized" message when you try to run a program, that‘s likely the culprit.

First things first—check to see if there‘s a 64-bit update available for the app in question. Visit the developer‘s website and look for a Catalina-compatible version. No dice? It may be time to cut ties and find a more modern 64-bit alternative.

Some users have also reported missing files and data after upgrading, particularly when using Migration Assistant. Before you panic, do a thorough search of your Mac to see if the files simply ended up in an unexpected location.

If the files are indeed missing, you have a few options. If you used Migration Assistant, try re-running the utility and double check that all of your user data is selected for transfer. If that doesn‘t work, you‘ll need to manually copy over the missing files from a backup or your old Mac.

Reverting to Mojave

Despite your best troubleshooting efforts, you may reach a point where you simply can‘t get Catalina running acceptably on your Mac. Maybe you‘re dead in the water without a certain 32-bit app, or you‘re tired of fighting with incompatibilities and glitches. In that case, you have the nuclear option of rolling back to macOS Mojave.

There are two ways to downgrade from Catalina to Mojave: restoring a full Time Machine backup, or reinstalling macOS from scratch.

If you had the foresight to create a complete Time Machine backup right before upgrading to Catalina, you‘re in luck. Simply restart your Mac while holding down Command+R to enter Recovery Mode. Select Restore From Time Machine Backup, choose your pre-Catalina backup, then click Restore and wait.

If you don‘t have a pre-upgrade Time Machine backup, you‘ll need to do a clean install of Mojave. Here‘s the process:

1. Restart your Mac in Recovery Mode by holding Command+R at startup.
2. Select Disk Utility, choose your startup disk, then click Erase.
3. Quit Disk Utility, then choose Reinstall macOS.
4. Follow the prompts to reinstall Mojave.

Once you‘re back on Mojave, you can use Migration Assistant or manually transfer your files to get your data back in place.

Migration Assistant Best Practices

Using Migration Assistant is convenient, but it‘s not foolproof. Follow these tips to improve your odds of a fast, hassle-free transfer:

• Clean before migrating: The leaner your old system, the easier the migration. Uninstall unused apps, clear caches, and tidy up files before running Migration Assistant.
• Use a wired connection: When migrating from an old Mac, using a Thunderbolt or USB-C cable instead of Wi-Fi can dramatically improve transfer speeds.
• Be selective: Don‘t just blindly click the Transfer Everything button. Take a minute to review the list of items to be transferred and uncheck anything you don‘t need, like unused apps or deprecated settings.
• Slim down your Photos: Got a giant Photos library? Consider syncing it to iCloud before migrating so you only transfer optimized versions of your pics.
• Update your software: Make sure your old Mac has all available macOS updates and your key apps are running the latest versions before migrating. The newer the data, the better the transfer.

When to Wait on Upgrading

As with any major new macOS release, it‘s not always wise to upgrade to Catalina on day one. If you rely on a specific app to get work done, verify that it‘s Catalina-compatible before taking the plunge. Remember, 32-bit apps won‘t run at all on the new OS.

Older hardware is also more likely to struggle with Catalina. If your Mac is more than 5 years old or is still rocking a spinning hard drive, you may want to sit tight on Mojave for a while. Give the developer community some time to optimize their apps and work out any kinks.

If you‘re eyeing a new Mac purchase, it‘s often best to start fresh with a clean Catalina installation rather than migrating your data from an old machine. Use cloud storage or an external drive to ferry your important files to the new Mac, then take the time to manually reinstall your apps. You‘ll start off with a clean slate and avoid any lingering cruft.

Advanced Tips for Power Users

For Mac power users who want to leave no stone unturned in the battle against Catalina sluggishness, here are a few advanced tweaks worth trying:

• Disable/re-enable Spotlight: Catalina‘s Spotlight search indexes your entire hard drive to enable lightning-fast file and app lookups. Sometimes, though, that indexing process can monopolize your CPU. Open System Preferences > Spotlight > Privacy, then click the + button and add your startup disk to the list. Wait a few seconds, then remove it again. This will force Spotlight to rebuild its index from scratch.
• Manually delete cache files: Macs generate cache files to speed up frequently performed tasks, but over time those caches can become bloated and cause slowdowns. Use the Finder‘s Go to Folder command to navigate to ~/Library/Caches. Delete the contents of any folder with an application name. Don‘t delete the folders themselves, only the files inside.
• Disable login items: If your Mac takes forever to boot up, you may have too many programs set to launch automatically at login. Go to System Preferences > Users & Groups > Login Items, then remove any unnecessary apps from the list.
• Reset the Launchpad database: A corrupted Launchpad database can cause app crashes and slowdowns. Open Terminal and enter this command to reset it:

sqlite3 ~/Library/Application\ Support/Dock/*.db "DELETE FROM apps; DELETE FROM groups WHERE title<>‘‘; DELETE FROM items WHERE rowid>2;"; killall Dock

These advanced tactics are not for the faint of heart. If you‘re not comfortable mucking around in Terminal or manually deleting system files, it‘s best to stick with the more straightforward troubleshooting steps outlined earlier.

Conclusion

Slow performance after upgrading to macOS Catalina is a common complaint, but it doesn‘t have to be a permanent condition. Whether you used Migration Assistant or not, following the steps in this guide can help you identify and resolve performance bottlenecks and get your Mac humming along smoothly again.

Remember, the key to a fast Catalina experience is a clean installation on a properly spec‘d machine. If you have the luxury of starting fresh, you‘ll likely have a much smoother ride than if you migrate a bunch of digital baggage from your old setup.

If you‘re still on the fence about upgrading from an older macOS version, consider waiting for the first few rounds of Catalina stability updates before taking the leap. Let the earliest adopters deal with the bugs and incompatibilities while you bide your time and ensure your key apps and accessories are fully Catalina-ready.

With a little patience and a lot of troubleshooting tenacity, you‘ll be able to make the move to macOS Catalina and enjoy all of its new features without sacrificing performance. Happy upgrading!