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What Safari’s “Significant Energy” Warning Really Means
This warning will appear at the top of a tab, right above the content of a web page. It doesn’t mean that the web page has crashed or has become unresponsive, but rather, that the web page is consuming more resources than you might be comfortable with if you’re running on battery power.
Safari is telling you that keeping this web page active will deplete your battery faster, likely due to some element on the page like a script or embedded video. Advertisements can cause this problem as well since they often introduce a lot of overhead to a website.
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You can see the effects of Safari by opening Activity Monitor (Search for it in Spotlight or find it under Applications > Activity Monitor.). Click on the “Energy” tab, and then click on the “Energy Impact” column to reorganize it in descending order to see the most energy-intensive processes at the top.
At any time, you can also click on your battery icon in the top-right corner of the screen to see a list of apps that are using significant energy.
Things You Can Try
If you’re using the web page in question or you would like to keep it open regardless, there’s no harm in plugging your laptop into the mains and carrying on with whatever you were doing. This will counter the added power usage so that you can finish what you’re doing without losing battery power.
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Sometimes, the warning is triggered by an error and reloading the page can fix the issue. Don’t be surprised if the warning comes back again, though, particularly in the case of web applications like Google Sheets or Spotify’s web player. Rebooting your Mac can also help.
If Safari is out of date, it’s possible that the warning was caused by an incompatibility with an element on the web page. Try installing any outstanding updates under System Preferences > Software Update and trying again.
There are a few other things that you can try to improve Safari stability, too. While these are unlikely to fix this particular error, disabling plugins can keep you safe, and removing unused extensions might speed up your browser.
Keep a Second Browser Handy
Safari is probably the best browser for the majority of Mac users. It’s well-optimized for energy usage, integrates with Apple services like iCloud, and generally performs well in terms of compatibility and responsiveness.
With that in mind, it’s always a good idea to have a second or even a third browser installed for those times that you run into issues. We’d recommend Chrome or Firefox, the two best-supported browsers on the web.