Webpage using significant energy / memory on Mac

Same here. This began fairly recently. I have no Safari extensions, I have no apps that didn't come from the App Store. i have no keepers or cleaners and my etrecheck showed that my mac performance was excellent. I usually get this message when I'm on CNN or CBS and there is a video accompanying the news story. I've never had this before. I've been thinking I was hacked but obviously others here are experiencing this too.

I have recently purchased a new iMac 27". It replaces a 2014 Mac mini. I, too, continue to get that "warning", especially on Facebook. I never saw it on my Mini at all which was running the same OS and all else being equal. What would make the new machine do this I've wondered. I even called support and they were not able to assist at all. Now I see I'm actually not the only one with this issue which, at least, makes me feel a bit better....LOL. I've tried everything, resetting, running "First Aid" from Utilities, checking resolution, etc. and it still shows up. Seems to be only with Safari, not with Firefox. Hoping to see some response from someone who has come up with some type of reasonable explanation.

golfingal56 wrote:

Safari ... Other than the annoying message and one of my G5 games constantly crashing

I have been researching this issue and the useless "annoying" message, digging around in the Developer site, asking questions and getting zero response. So far I have turned up nothing.

An experimental feature(?) New WebKit Features in Safari 11.1 | WebKit

I realise that it only happens when opening Facebook on Safari. No problems with other webpages. Not sure if this is a problem with the Facebook webpage or Safari browser. So far nobody has a satisfying answer to this problem. Frustrating!!

I've been on the phone with Apple Care and then to the Genius Bar - neither could resolve the problem. At least the Genius Bar knew about the issue - Apple Care knew nothing. I'm now using Crome until Apple resolves this issue.
Please, Apple, find a solution to this...

If the above doesn't work, Safari/Preferences/Advanced - enable the Develop menu, then go there and Empty Caches. Quit/reopen Safari and test. Then try Safari/History/Show History and delete all history items. Quit/reopen Safari and test. You can also try try Safari/Clear History…. The down side is it clears all cookies. Doing this may cause some sites to no longer recognize your computer as one that has visited the web site. Go to Finder and select your user/home folder. With that Finder window as the front window, either select Finder/View/Show View options or go command - J. When the View options opens, check ’Show Library Folder’. That should make your user library folder visible in your user/home folder. Select Library/Caches/com.apple.Safari/Cache.db and move it to the trash.

Go to Safari Preferences/Extensions and turn all extensions off. Test. If okay, turn the extensions on one by one until you figure out what extension is causing the problem.

Safari Corruption See post by Linc Davis

If that doesn't work, try running this program in your normal user account , then copy and paste the output in a reply. The program was created by etresoft, a frequent contributor. Please use copy and paste as screen shots can be hard to read. On the screen with Options, please open Options and check the bottom 2 boxes before running. Click “Share Report” button in the toolbar, select “Copy Report” and then paste into a reply. This will show what is running on your computer. No personal information is shown.

Etrecheck – System Information

Did you try disabling the Safari extensions?

Most posters recommend not using cleaning programs. They can destroy normal computer operations.

CleanMyMac3 Uninstall

Check for associated parts and pieces using these programs.

EasyFind – Spotlight Replacement

Find Any File

Try setting up another admin user account to see if the same problem continues. Also try the Safe Mode.

Isolating an issue by using another user account

Safe Mode - About El Capitan
also Sierra

Safe Mode Startup – El Capitan. also Sierra

tekey wrote:

I have done everything asked to get rid of this and nothing has worked. It's frustrating when the pop up occurs and even more so when the page automatically refreshes because of this.

See this thread: Re: Safari message stating "this webpage is using significant energy"

Some things are out of your control. I see this as a non-issue. Safari is working in your behalf to keep everything running smooth as possible in it's rendering engine.

My only suggestion is you could try a different browser and see if it renders the page any more efficiently.

Frogmom09 wrote:

Seems to be only with Safari, not with Firefox. Hoping to see some response from someone who has come up with some type of reasonable explanation.

What is the saying—"you can lead a horse to water but you can not make him drink."

Re: Safari message stating "this webpage is using significant energy"

It is the new Safari updated with 10.13.x-10.13.4, everything is working as it should. I do not notice any slow down or disruption to Safari in all honesty, besides the pop-up banner. This may be a clue that Safari is working as efficiently on your behalf to keep things running smooth behind the scenes.

Ignore the warning if you wish, or excuse it by the x. There is absolutely no user harm either way. I suspect if (like before the new Safari) you did not get the warning, you would be non-the-wiser.

Just because Safari is "made for Mac," it has no control over half baked code a website is running. (Maybe that would be the better warning message.) A resource intense interface. As you can imagine CNN, Facebook run some realtime API's that not all rendering engines interpret in same way. This is by design or there would be no difference or need for different browsers. Think of it this way that warning message keeps people employed. 😉

If this troublesome warning message popped up on every other website—then yes Safari has a problem. It simply is not case, from your post, other post on ASC, or my own user experience.

By all means send Apple Feedback http://www.apple.com/feedback/

Please note I am not an apologist for the Safari.app I just see it as a non-issue. Surely there are bigger fish to fry.

leroydouglas wrote:

I would not waste your time.

It is not your issue to be resolved. Frustrating maybe, but out of your hands.

The best you can do is try a different browser that using a different rendering engine than Safari (which uses Webkit.)

An Alternative for ex. Firefox use Gecko.

Apple Feedback http://www.apple.com/feedback/

Frogmom09 wrote:

I realized I do not have the "Develop" option as part of my Safari.

If you don’t see the Develop menu in the menu bar, choose Safari>Preferences>Advanced> “Show Develop menu in menu bar.”

https://support.apple.com/guide/safari/use-the-safari-develop-menu-sfri20948/mac

Mine started in early April with system update to 10.13.4 which was released on March 29, 2018. The previous version was released in January and I did not have this issue in March or earlier. That's why I think it was the update to 10.13.4.

Mine happens when I stream video with MLB.com.

There's another thread started at the same time when this issue started,

Problem with High Sierra 10.13.4