You just spent real money on a new Mac and it feels sluggish. That's a frustrating experience, and your instinct to investigate it is right. But before you conclude something is wrong, it helps to know that the first 24 to 48 hours on a new Mac are unusually demanding. Several background tasks that only run once are all happening at the same time, and they consume memory and CPU in ways that will not repeat once setup is done. Most people who feel their new Mac is slow in this window discover it's perfectly fine a day or two later.
That said, not all of this resolves on its own. Let's go through the four main causes in order of how likely they are.
The first 24-48 hours: indexing and syncing (give it time)
When you first turn on a new Mac and sign into your Apple ID, three things happen at once.
Spotlight indexes your drive. Spotlight, the search feature behind Command-Space, needs to build a complete index of every file on your Mac before it can return search results. On a fresh Mac with nothing on it this is quick. On a Mac you've just migrated from a backup or filled with iCloud files, it can take hours. While indexing is running, a process called mds or mds_stores will show up in Activity Monitor consuming significant CPU. This is normal and temporary. You can check its progress by opening Spotlight (Command-Space) and searching for something; if you see "Indexing..." at the bottom of the results, it's still running.
iCloud syncs your files and photos. The first time you sign into iCloud on a new Mac, it begins downloading your Desktop, Documents, and any other iCloud Drive folders. If you have iCloud Photos enabled and a large library, this runs in the background for hours. A process called bird handles iCloud Drive syncing; cloudd handles Photos. Both can use substantial CPU and memory while catching up. You'll see a circular progress indicator on folders in Finder while this is happening.
System preferences and app metadata are being configured. First-launch of many apps involves generating caches, compiling shaders, and indexing their own content. This settles quickly for individual apps but adds up when you open many things for the first time on day one.
The practical advice here is straightforward: leave the Mac plugged in overnight on the first night. Let it finish. Most people report that a Mac that felt sluggish on day one feels noticeably snappier by the end of day two.
The 8GB-on-Apple-Silicon question (honest answer: enough for some, not for power users)
Apple Silicon Macs use unified memory, which means the same pool of RAM is shared between the CPU and the GPU. Apple argues this makes 8GB go further than 8GB of traditional RAM because there's no copying data between separate pools. That's true to a meaningful degree.
For a certain kind of user, 8GB is perfectly fine. If you mainly write documents, browse the web with a reasonable number of tabs, manage email, use communication apps like Slack, and watch video, an 8GB MacBook Air can handle all of that without visible memory pressure most of the time.
But "enough" has limits. If you work with large spreadsheets, run video editing software like Final Cut or DaVinci Resolve, use Xcode with a simulator running, keep 30+ browser tabs open across Chrome or Firefox, or run virtual machines, 8GB will become a constraint. You will see the memory pressure graph in Activity Monitor turn yellow or red regularly. The Mac will start swapping to storage, and even on a fast SSD, that's noticeably slower than RAM.
The deeper question of whether 8GB or 16GB is right for your workload is covered in full in 8GB vs 16GB Mac: which do you actually need. There's also a more specific look at whether an M1 MacBook Air with 8GB is still worth buying in 2026 if you're weighing an older model. The general RAM question is addressed in how much RAM you actually need on a Mac.
Migration Assistant brought your old slowness with you (login items, kexts, Adobe leftovers)
Migration Assistant is genuinely useful: it transfers your apps, documents, preferences, and settings from your old Mac to your new one. The problem is that it transfers everything faithfully, including the things that were slowing your old Mac down.
Over years of use, a Mac accumulates background processes. Every app you install has the opportunity to add a login item, a launch agent, or a launch daemon. Many do. Adobe apps are a particular example: installing Creative Cloud adds several helper processes that run at startup and stay running all the time. Dropbox, Google Drive, security tools, and various utilities all do similar things. On your old Mac these built up gradually and you never noticed. On your new Mac they all show up on day one, imported wholesale from the backup.
To check what's running at startup, open System Settings, go to General, then Login Items and Extensions. Look at the "Open at Login" list and the "Allow in Background" list. Remove anything you don't recognise or don't actively use. This alone can make a meaningful difference.
The other Migration Assistant trap is carrying over old macOS extensions, kernel extensions, or system modifications. These sometimes cause compatibility issues with new macOS versions and can contribute to slowness in ways that are hard to diagnose. If you're willing to do a clean install rather than a migration, it's often the fastest path to a genuinely fresh-feeling Mac, though it means reinstalling your apps manually.
New macOS version, new bugs (link to Sequoia/Tahoe posts)
Occasionally, the issue is neither the hardware nor your setup; it's the operating system itself. Major macOS releases sometimes ship with memory leaks, runaway processes, or performance regressions that Apple fixes in subsequent point releases.
A well-known pattern: a process behaves normally on macOS 14 but consumes abnormal memory on macOS 15 due to a code change that introduced a leak. The user experiences this as slowness that wasn't there before, often without any obvious cause in Activity Monitor because the leak is in a system process rather than an app.
If your Mac started feeling slow after a macOS update, check Apple's support pages and tech news sites for reports of similar behaviour. Search for the macOS version name plus the word "slow" or "performance" and see if others are reporting the same issue. Apple typically patches these within one or two point releases. In the meantime, keeping your apps updated is still worth doing, as sometimes the issue is in an Apple app like Safari or Mail rather than the OS itself. For specific version-related issues, look at the posts on macOS Tahoe performance for the latest.
Apple's own Activity Monitor user guide is a useful reference for understanding what each process does and whether its resource use is abnormal.
What to actually check (Activity Monitor first, then login items, then exchange-or-keep decision)
After the first 48 hours, if your Mac still feels slow, here's the order to investigate.
Start with Activity Monitor. Press Command-Space, type "Activity Monitor", and press Return. Click the CPU tab and look for any process using a very high percentage consistently, not just a brief spike. Then click the Memory tab. Look at the Memory Pressure graph at the bottom. Green means you're fine. Yellow means you're running tight. Red means memory pressure is genuinely impacting performance and is the likely cause of slowness. Sort the app list by the Memory column to find the biggest consumer.
If you see mds_stores, bird, or cloudd at the top and it's been less than 48 hours, leave it alone. If it's been four or five days and those processes are still consuming significant CPU, something is stuck and worth investigating further.
Then check login items. As described above, open System Settings › General › Login Items and Extensions and trim the list. After removing unnecessary items, restart the Mac and check whether Activity Monitor looks calmer.
Then make the exchange-or-keep decision. If Activity Monitor shows consistent red memory pressure even after clearing out login items and giving the Mac a few days to finish setup, and your workload is legitimately demanding, the honest answer may be that 8GB isn't enough for how you work. If you're within your return window, you have a real decision to make. If you've had the Mac for a while, the options are managing what you run (fewer tabs, quitting apps you're not using, being selective) or accepting the limitation.
Either way, the place to start is always observation rather than assumption. Activity Monitor gives you the actual data, and the actual data is usually reassuring, at least once the first 48 hours are done.