Safari Web Content, Chrome Renderer very high CPU usage

[rex3]

I recently got a rMBP with ML, but my battery life is terrible. Mostly it seems to be because Safari Web Content regularly uses 40-80% of my CPU usage in Activity Monitor. I switched to Chrome, but then Chrome Renderer uses 30-50% a lot of the time.

What's going on? My old MBA had much better battery life than my new rMBP. Help!!

 

[ObeseSquirrel]

I have this exact same problem. The only way I have found to solve it in Safari is to disable javascript. Not very acceptable.

Edit: Confirmed that this is not from Flash, Extensions, Plugins, or Java.

 

[GGJstudios]

Frequently, the culprit is Flash content on websites. For Flash-related issues:

• Find your Flash version and make sure it's the latest version available. Never install or update Flash from a pop-up on a website. Always go to Adobe's site to get Flash or updates.
• Install ClickToFlash (Safari), Flashblock (Firefox) or FlashBlock (Chrome) to control which Flash content plays on websites.
• Try using the YouTube HTML5 Video Player to watch YouTube videos, when available. (May impact fullscreen viewing. See link for details.) Some have reported better performance with HTML5, while some have reported worse. Try it and find out what works best for you.

There are many factors that impact your battery life. See the BATTERY LIFE FROM A CHARGE section of the following link for details, including tips on how to maximize your battery life.

This should answer most, if not all, of your battery/charging questions:

Apple Notebook Battery FAQ​