Pages crawling to load. Scrolling that stutters. Your fan spins up just from opening a news article. If Safari’s gone from snappy to sluggish, that’s genuinely annoying. But you don’t need to switch browsers or wipe your Mac to fix it. The usual suspects are too much stored website data, a misbehaving extension, a runaway tab, or a macOS version that’s fallen behind. Your network, low free storage, or the website itself can also be to blame, so this guide helps you tell those apart too.
This guide walks through the fixes in order, from safest to most invasive. Follow them in sequence, and you’ll likely be back to fast browsing before the last step.
Why Safari Slows Down Over Time
Safari doesn’t get slower for no reason. It’s usually one of these, sometimes a combination:
- Cache and website data pile up. Every site you visit leaves behind cookies, cached images, and local storage to speed up your next visit. Over months of browsing, this can grow into gigabytes of clutter, some of it corrupted or stale.
- Extensions accumulate. Ad blockers, password managers, and shopping tools are handy, but each one runs code on every page you load. A poorly optimized extension can quietly slow things down.
- A single tab goes rogue. Autoplaying video, crypto-mining scripts, or a poorly coded site can pin a CPU core and drain your battery. This happens even in a background tab you forgot about.
- macOS falls behind. Safari isn’t a standalone app you update from the App Store. Its updates arrive through macOS Software Update. If you’ve been putting off software updates, you’re missing Safari performance and security fixes too.
The good news: none of these require reinstalling anything. Let’s go through the fixes.
Before You Begin
Make sure you have:
- A Mac running macOS Sequoia or later (check your version in Apple menu > About This Mac)
- Safari open and updated to the version bundled with your current macOS
- About 15–20 minutes to work through the checklist
- An admin password handy, in case macOS prompts you during a software update
| Requirement | Details |
|---|---|
| Device | Any Mac (Apple silicon or Intel) |
| OS version | macOS Sequoia or later recommended (the current release is macOS 27 Golden Gate, out since September 14, 2026; menu names can differ slightly on older versions) |
| Account | No Apple ID required for these fixes |
Step-by-Step Guide
Step 1: Clear Cache and Website Data (Without Losing Passwords or Bookmarks)
This is a low-risk first check, and it often helps when Safari has slowed down gradually over months. If only one site misbehaves, remove just that site’s data (see the tip below) before reaching for Remove All. Clearing website data does not delete your bookmarks, Reading List, or saved passwords. Those live in separate, protected storage.
- Open Safari and go to Safari > Settings (or press
Cmd + ,). - Click the Privacy tab.
- Click Manage Website Data.
- A dialog opens listing every site with stored data, plus how much space it’s using. You can:
- Select a specific site and click Remove to clear just that one.
- Type a site name in the search field to jump to it.
- Click Remove All to clear everything at once.
- Click Done to confirm.
Tip: If only one site feels slow or glitchy, not Safari overall, skip the full wipe. Search for just that site in Manage Website Data and remove it, then reload the page. Note this will sign you out of that specific site.
Warning: Remove All signs you out of every website you’re currently logged into. Your saved passwords in iCloud Keychain won’t be affected, but you’ll need to log back in manually on sites that don’t use saved credentials.
Step 2: Audit and Disable Problematic Extensions
A misbehaving extension is a frequent suspect, especially if the slowdown started right after you installed something new.
- Go to Safari > Settings > Extensions.
- You’ll see every installed extension with a checkbox next to it. If you use Safari profiles, extensions are turned on or off separately in each profile, so check the Extensions settings of the profile you’re browsing in.
- Uncheck one extension at a time. Then reload a page you know is slow (
Cmd + R) and see if performance improves. - If a specific extension is the culprit, leave it turned off, or select it and click Uninstall to remove it. For an extension that came with a Mac app, deleting that app also removes the extension.
Tip: If you rely on an ad blocker or password manager, don’t uninstall it blindly; just disable it temporarily. Many extensions have their own settings for reducing background activity instead of removing them entirely.
Worth doing this even when nothing feels broken. Review your full extension list every few months instead of waiting until something slows down.
Step 3: Check Whether Safari Is Using Excessive CPU or Energy (Activity Monitor)
If your Mac’s fans spin up or the battery drains fast while you’re just browsing, a single busy tab is often the cause, not Safari as a whole. Activity Monitor confirms whether Safari is the drain; closing tabs one by one then finds the culprit.
- Open Finder > Applications > Utilities > Activity Monitor (or search for it with
Cmd + Spaceand typeActivity Monitor). - Click the Energy tab along the top.
- Click the Energy Impact column header to sort processes from highest to lowest impact.
- Look for entries labeled Safari Web Content near the top of the list. Safari splits its work across several background processes, and Activity Monitor generally doesn’t label each one with the specific tab it belongs to, so you can’t reliably match one listed process back to one exact open tab. What this step actually tells you is whether Safari, in aggregate, is using a disproportionate share of energy or CPU, not which single tab is responsible.
- To pin down the actual culprit, switch to Safari and close tabs one at a time, watching the Energy Impact number after each close, or use Tab > Close Other Tabs to test in batches (divide and conquer). Check first any tabs that are playing video or animation, or that auto-refresh content, since those are the most common real causes of a single tab hogging resources.
Tip: You can also check the CPU tab the same way if a tab is spiking processor usage rather than draining battery; sort by % CPU instead of Energy Impact.
Safari also has a built-in shortcut for narrowing things down. Open Window > Show All Tabs, or the tab overview grid (Shift + Cmd + \). Audio and activity indicators there can help you spot a noisy tab visually, which pairs well with the close-and-test approach above since Activity Monitor alone won’t point you to a specific tab.
Step 4: Turn Off Experimental Safari Features (Feature Flags)
Safari’s Develop menu includes a Feature Flags panel that lets web developers turn individual WebKit features on or off for testing, including features that are still in preview. Those settings aren’t meant for everyday browsing, so if one got changed from its default, by you or during a past troubleshooting session, it’s worth putting back.
- Go to Safari > Settings > Advanced.
- Check the box for Show features for web developers (this enables the Develop menu in the Safari menu bar).
- In the menu bar, click Develop > Feature Flags.
- Look for features shown in bold, which marks a feature changed from its default. If you don’t specifically remember changing one for a reason, switch it back to Safari’s default.
Tip: If you’ve never intentionally opened Develop > Feature Flags before, it’s unlikely anything here is causing your slowdown. But it takes 30 seconds to confirm, so it’s worth ruling out before moving to bigger fixes.
Step 5: “Reset” Safari the Current Way: Clear Data, Extensions, and Advanced Settings
Older versions of Safari had a single Reset Safari command that cleared everything at once. Apple removed it back in Safari 8 (OS X Yosemite). In the current version, a full reset is really the combination of the steps you’ve already done:
- Clear all website data (Safari > Settings > Privacy > Manage Website Data > Remove All, see Step 1).
- Disable or remove all non-essential extensions (Safari > Settings > Extensions, see Step 2).
- Turn off any custom Advanced settings you don’t recognize, including Feature Flags (Safari > Settings > Advanced, see Step 4).
- Optionally, clear your browsing history separately via History > Clear History. Choose a time range from the dropdown. This is distinct from website data and doesn’t touch bookmarks or passwords.
Doing all four together is effectively today’s version of “resetting” Safari. There’s no all-in-one button. Keep in mind that removing all website data signs you out of websites, although it doesn’t delete your bookmarks or the passwords saved in your keychain.
Step 6: Confirm macOS and Safari Are Up to Date
Safari isn’t updated through the App Store as a standalone app. Apple delivers Safari updates through Software Update, as part of macOS updates (and sometimes as a separate Safari update for older supported macOS versions). If you’ve been ignoring update prompts, you could be missing real performance and security fixes.
- Click the Apple menu > System Settings.
- Click General in the sidebar, then click Software Update.
- If an update is available, click Update Now or Upgrade Now. Your Mac will download it, and you’ll be prompted to restart.
- Once updated, open Safari and check Safari > About Safari to confirm the version number has changed.
Tip: Turn on Automatically keep my Mac up to date in this same panel so you’re not chasing Safari performance bugs that Apple already patched months ago.
Step 7: When to Consider a Clean Profile (Last Resort)
Say you’ve cleared cache, disabled extensions, checked Activity Monitor, ruled out Feature Flags, and confirmed macOS is current, and Safari is still slow. The problem may be tied to accumulated profile-level data or, rarely, something system-wide.
Try a Safari Profile first. It’s much less drastic than a new macOS user account:
- Go to Safari > Settings > Profiles.
- Click the + button to create a new profile. Each profile gets its own history, cookies, website data, and favorites, kept separate from your main profile. Extensions are shared across all profiles, but they’re turned off by default in a brand-new profile; you turn individual ones back on per profile from that profile’s own Extensions tab. That makes a fresh profile a convenient, extensions-off test environment out of the box.
- Switch to the new profile and browse for a day. If it’s noticeably faster, your original profile’s accumulated data, not Safari itself, was likely the cause.
Only if that doesn’t help, test with a brand-new macOS user account (System Settings > Users & Groups > +) to rule out a system-level issue outside Safari entirely. This is a genuine last resort. Most people never need to go this far, so don’t jump here first.
If Something Goes Wrong
If Safari is still slow after working through every step above, try these quick checks:
- Restart your Mac. This clears memory pressure that builds up over days of uptime.
- Quit Safari completely (
Cmd + Q), then reopen it while holdingShiftto skip reopening your last session’s tabs. - Test the same slow website in a Private Browsing window (
Shift + Cmd + N). Private Browsing opens a separate browsing context that doesn’t use your existing cookies and isn’t saved to your normal history, but that’s not the same as disabling extensions: on macOS Sonoma and later, extensions that need website access are off by default in Private Browsing windows unless you’ve specifically turned on Allow in Private Browsing for that extension (Safari > Settings > Extensions > select the extension). If you want a clean test that fully rules out extensions, disable them directly using Step 2 rather than relying on Private Browsing alone. - Test on a different Wi-Fi network, and temporarily turn off any VPN or network-filtering security software, to rule out a network-level issue rather than a Safari one.
- Check whether the slowdown is Safari-only. If other browsers and apps are sluggish too, look at free storage (Apple menu > System Settings > General > Storage) and the Memory Pressure graph in Activity Monitor’s Memory tab instead.
Common Issues
Safari is slow across every website
Why it happens: Accumulated cache and website data, a problematic extension, or an outdated macOS/Safari version.
Fix: Work through Steps 1–3 in order: clear website data, check extensions, then confirm macOS is current.
One tab makes the whole Mac slow or hot
Why it happens: A single tab, often autoplaying video or a poorly coded ad, is consuming excessive CPU or energy in the background.
Fix: Use Activity Monitor’s Energy tab (Step 3) to confirm Safari is the drain, then close tabs one at a time until the energy use drops.
A specific website is slow or broken, but others work fine
Why it happens: Corrupted or oversized cookies and cache for that one site.
Fix: Test the site in a Private Window. If it loads fine there, remove just that site’s data via Manage Website Data (Step 1) instead of clearing everything.
Safari became slow right after adding an extension
Why it happens: A third-party extension is interfering with page rendering or running background scripts on every page.
Fix: Disable extensions one at a time in Safari > Settings > Extensions and reload the affected page after each toggle.
Safari keeps reopening unwanted pages or feels stuck
Why it happens: Safari tried to reopen your previous session, which included a problematic or unresponsive page.
Fix: Quit Safari (Option + Command + Esc to Force Quit if it’s unresponsive), then reopen it while holding Shift to skip restoring the last session.
Tips and Hidden Features
- Test with Private Relay diagnostics: If iCloud Private Relay (part of iCloud+) is active on your network, choose View > Reload and Show IP Address on a slow page. That turns Private Relay off for that site until you leave it or close the tab; if the page is suddenly faster, Private Relay may be involved on that connection.
- Report slow sites to Apple: In Safari 26 or later, reload the problem page, click the Page Menu button in the Smart Search field, and choose Report a Website Issue.
- Keep external accessories in mind: If you’re routing Safari through a docking setup, say, a Thunderbolt dock or a USB-C hub feeding an external display, a flaky connection can sometimes look like browser lag instead of a display issue. Worth ruling out if slowdowns start right after plugging in.
- Back up before drastic steps: If you’re about to test a new user account, plug in an external SSD and make sure Time Machine has a recent backup first.
Wrapping Up
In many cases, a slow Safari comes down to bloated website data or one misbehaving extension, and both are quick fixes. Work through the checklist in order and test after each step. You’ll usually catch the culprit before you ever touch Activity Monitor or create a new profile.
If you made it all the way to Step 7, that’s unusual. The good news: you’ve now ruled out Safari’s most common culprits, which narrows down what’s left to check.
| Step | Action | Applies To |
|---|---|---|
| 1 | Clear cache and website data | General slowdowns, site-specific glitches |
| 2 | Disable/remove problematic extensions | Slowdowns after installing new tools |
| 3 | Check Activity Monitor’s Energy tab | One tab causing heat/battery drain |
| 4 | Turn off experimental Feature Flags | Instability after enabling dev features |
| 5 | Combine data + extensions + Advanced reset | Full “reset Safari” equivalent |
| 6 | Update macOS via Software Update | Outdated Safari version |
| 7 | Create a Safari Profile or new user account | Persistent slowdowns after all else fails |