Quick fixes to "Webpage using significant energy" error

Remember the days when every time we'd open a new webpage in Safari, it would launch a new window? Just a few of those, and you're completely lost! But since the adoption of tabs, everything became more organized, which, in turn, allowed us to keep dozens of them open at once.

If only we'd known the toll it would take on our machines. Some people today pay a lot extra for powerful rigs with the only goal to support their 100+ tab habit. You might be a bit of a tab hoarder yourself (no judgment, I am as well) if you've ever seen the "This webpage is using significant energy. Closing it may improve the responsiveness of your Mac." message in Safari. But don't run to the Apple Store for an upgrade yet — try these few ways outlined below first.

What to do when Safari is overloaded

The underlying reason for the "This webpage is using significant energy" error is your Mac's resources being stretched too thin, which might either be the result of too many tabs open or even just a few tabs with websites that are continuously refreshing and loading up new scripts and content. 

So the first thing to do is simply decrease the number of tabs by closing some (use the ⌘ + W shortcut). Alternatively, you can try to reload Safari completely. To do that, go to Safari in the menu bar and then select Quit Safari, or use the shortcut ⌘ + Q. If none of that had any result, proceed with a few more steps. 

Tip: The problem is often site-specific. So deciding which tabs close, start with online editors or streaming websites because they use lots of RAM.

1. Empty Safari's cache and cookies

Like any other browser, Safari accumulates lots of information about the websites you visit and the information you share. All this is recorded in your cache and cookies, which might become too power-taxing over time.

To clean your cache in Safari: 

  1. Go to Safari > Settings in the menu bar (or use ⌘ + ,).
  2. Navigate to the Advanced tab and check the box "Show Develop menu in menu bar."
  3. Now select the Develop menu in the Menu bar and click on Empty Caches.
  4. Restart Safari to make sure the cache is clear.

In addition, it could be beneficial to delete your cookies:

  1. Open Settings once again.
  2. Go to the Privacy tab > Manage Website Data…
  3. Press ⌘ + A to select all fields.
  4. Remove All.

Your Safari experience should become faster now, so the "This website is using significant energy." error might already be gone. 


If you don't want to clear caches manually, I have a ready-to-use recommendation for you. Just use CleanMyMac X, and the app will do everything for you. It can clear caches in all browsers at once in a matter of seconds. 

To clear caches, follow these steps:  

  • Open CleanMyMac X (download it for free here).
  • Go to System Junk tab. 
  • Hit Scan. 
  • The app will detect all of the junk files your system stores and offer the Clean option after the scan is complete.

2. Turn off all Safari extensions

Another power-hogging aspect of any browser is its extensions. So, disabling them might actually help the problem, especially if you have lots going on at the same time. 

To turn off Safari extensions:

  1. Fire up settings (⌘ + ,).
  2. Go to Extensions.
  3. Uncheck all boxes to disable your extensions. 
  4. Restart Safari to see if the error has disappeared.

Bonus: You can try turning extensions on one by one to see which of them really needs too much power.

3. Free up RAM for a faster system

Safari is showing you the "This website is using significant energy." error because it has consumed all the available RAM. But other apps use RAM too. So freeing up that memory will give Safari more resources to utilize.

How do you free up RAM? Restarting your Mac is a quick but not a long-term solution. For immediate effect, you need to use a special tool like CleanMyMac X.

CleanMyMac X is a Swiss-knife utility designed to optimize all areas of your Mac. And resetting your RAM with it just takes a few clicks:

  1. Download a free version of CleanMyMac X.
  2. Open the app and navigate to the Maintenance tab, under Speed.
  3. Click Free Up RAM and then Run.

This app is notarized by Apple, so you know it's a safe option to try in this case.

4. Check for mining scripts

Some cryptocurrency miners are lucrative enough to spread their demands to hundreds of internet users out there. Bad actors infect some websites with notorious scripts. They cannot affect your system significantly, but they may consume its resources. Note that, for some websites, such as online tools or online editors, high energy use is normal. But if you see this message while surfing a supposedly normal website, check if it does not use mining scripts. AdBlock extension for Safari helps detect them. So, you'd better keep it installed and disable other extensions.

5. Update macOS

Newer OS versions offer more tools for better performance and improved resource management. If you have not updated macOS for a while, it may be a step you need to take. The best practice is to install the newest macOS updates. In most cases, they will include bug fixes, but Safari updates may come in the package.

To do it, follow these steps:

  1. Go to Apple menu in the upper left corner of the screen.
  2. Navigate to System Settings > General.
  3. Open Software Update.
  4. Click Upgrade Now if new macOS versions are available.
System Preferences - Software Update

It's likely that the "significant energy" message is now gone. However, it's good to make sure it doesn't appear again by optimizing the apps that use a lot of memory and processing power.

CleanMyMac X will help you here as well:

  1. Get a free edition of the app.
  2. Open and go to the Optimization tab.
  3. Click on Heavy Consumers, check all the apps listed, and then Perform.
  4. Choose one from the list and hit Quit.

At last, your Mac is fully optimized with a little help from CleanMyMac X🙂 In fact, using this or similar Mac optimization app, you can skip all the manual steps of clearing your cache files and cookies and turning off extensions and simply let the program to do the work for you in just a few seconds. 

Laptop with CleanMyMac
CleanMyMac X

Your Mac. As good as new.