Q: Severe memory leak detected in Latest Safari 9.0 update.

You need to uninstall CleanMyMac. It is horrible for your system, and can actually damage it. It deletes files it shouldn't, and you won't know this until things mysteriously stop working.  All you have to do is search around here to see hundreds, if not thousands of people, all describing the various problems they've had with this program, along with MacKeeper and any other program that promises to "clean," "maximize," or "optimize" your hard drive.  They can and will do no such thing.

The problem with your computer is not Safari, it's CleanMyMac.

You don't need Memory Cleaner either.  Macs don't require these kinds of programs in order to run efficiently.  I don't know why people think they do, but they don't.  I'll repeat myself, there is no program out there that will actually "clean," "optimize," or "maximize" any part of your system. 

Please read this whole message before doing anything.

This procedure is a test, not a solution. Don’t be disappointed when you find that nothing has changed after you complete it.

Step 1

The purpose of this step is to determine whether the problem is localized to your user account.

Enable guest logins* and log in as Guest. Don't use the Safari-only “Guest User” login created by “Find My Mac.”

While logged in as Guest, you won’t have access to any of your documents or settings. Applications will behave as if you were running them for the first time. Don’t be alarmed by this behavior; it’s normal. If you need any passwords or other personal data in order to complete the test, memorize, print, or write them down before you begin.

Test while logged in as Guest. Same problem?

After testing, log out of the guest account and, in your own account, disable it if you wish. Any files you created in the guest account will be deleted automatically when you log out of it.

*Note: If you’ve activated “Find My Mac” or FileVault, then you can’t enable the Guest account. The “Guest User” login created by “Find My Mac” is not the same. Create a new account in which to test, and delete it, including its home folder, after testing.

Step 2

The purpose of this step is to determine whether the problem is caused by third-party system modifications that load automatically at startup or login, by a peripheral device, by a font conflict, or by corruption of the file system or of certain system caches.

Please take this step regardless of the results of Step 1.

Disconnect all wired peripherals except those needed for the test, and remove all aftermarket expansion cards, if applicable. Start up in safe mode and log in to the account with the problem.

Note: If FileVault is enabled in OS X 10.9 or earlier, or if a firmware password is set, or if the startup volume is a software RAID, you can’t do this. Ask for further instructions.

Safe mode is much slower to start up and run than normal, with limited graphics performance, and some things won’t work at all, including sound output and Wi-Fi on certain models. The next normal startup may also be somewhat slow.

The login screen appears even if you usually log in automatically. You must know your login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin.

Test while in safe mode. Same problem?

After testing, restart as usual (not in safe mode) and verify that you still have the problem. Post the results of Steps 1 and 2.

I am also having the same problem. I tried everything you said and it didn't hang in guest profile but it did in safe mode. What does that mean? I took screen shots of activity monitor and system profile if you want to see them. They have my UUID and Serial, is that safe to post here?

I am also having the same issue.

Safari only, in a matter of minutes my memory (8GB) will be gone and i will receive a pop-up stating i have run out of memory.

Safari requires me to Force quit it at that time, and also when i attempt to close it just after having it open for 30 seconds or so.

I don't use any third-party programs like Clean My Mac, and i haven't had any other issues besides this.

pinkstones, please take this seriously. You are doing us all a massive disservice by blaming third-party software and not diagnosing the issue properly.

Memory leaks and CPU usage – solve - Yosemite

I tried this, it did not work.

Resetting Safari worked for me:

Open a terminal and enter the following commands to fully wipe out all of your old Safari settings:

mv ~/Library/Safari ~/Desktop/Safari-`date +%Y%m%d%H%M%S`; \ rm -Rf ~/Library/Caches/Apple\ -\ Safari\ -\ Safari\ Extensions\ Gallery; \ rm -Rf ~/Library/Caches/Metadata/Safari; \ rm -Rf ~/Library/Caches/com.apple.Safari; \ rm -Rf ~/Library/Caches/com.apple.WebKit.PluginProcess; \ rm -Rf ~/Library/Cookies/Cookies.binarycookies; \ rm -Rf ~/Library/Preferences/Apple\ -\ Safari\ -\ Safari\ Extensions\ Gallery; \ rm -Rf ~/Library/Preferences/com.apple.Safari.LSSharedFileList.plist; \ rm -Rf ~/Library/Preferences/com.apple.Safari.RSS.plist; \ rm -Rf ~/Library/Preferences/com.apple.Safari.plist; \ rm -Rf ~/Library/Preferences/com.apple.WebFoundation.plist; \ rm -Rf ~/Library/Preferences/com.apple.WebKit.PluginHost.plist; \ rm -Rf ~/Library/Preferences/com.apple.WebKit.PluginProcess.plist; \ rm -Rf ~/Library/PubSub/Database; \ rm -Rf ~/Library/Saved\ Application\ State/com.apple.Safari.savedState

Restart your machine and check memory usage again

Hope this works.

On your own head be it, then.  CleanMyMac is junk, just like MacKeeper and any other similar product.  I don't know how many people here have to say this before people figure it out and listen.  There is nothing CleanMyMac purports to do that your own gray matter can't do as well.  That's all a Mac needs, by the by, to stay in good working order.  It doesn't need cleaners, refreshers, optimizers, anti-virus software, extra firewalls, or anything else like that.  Apple does a fairly decent job of putting out a product that doesn't need extraneous third-party programs to run efficiently.

I can 100% guarantee you that CleanMyMac has not kept you out of trouble for years, especially since programs like that many times delete files that you need, files you won't know are missing until something goes wrong.  Not to mention, saying the program has kept you out of trouble is a bit like saying the rock under my bed keeps tigers away; because I haven't seen any tigers, therefore the rock is working.

CleanMyMac is a scam, and even if not related to your issue, it should not be installed.

I'll try it! Can I just copy and paste this?