MacBook Pro freezes frequently and runs slow.

Adware

1. Use free Malwarebytes Anti-Malware for Mac/ AdwareMedic to remove adware

http://www.adwaremedic.com/index.php

Download, install , open, and run it by clicking “Scan for Adware” button to remove adware.

Once done, quit Malwarebytes Anti-Malware.

or

Remove the adware manually by following the “HowTo” from Apple.

http://support.apple.com/en-us/HT203987

2. Safari > Preferences > Extensions

Turn those off and relaunch Safari.

Turn those on one by one and test.

3. Safari > Preferences > Search > Search Engine :

Select your preferred search engine.

4. Safari > Preferences > General > Homepage:

Set your Homepage.

Third party software

Remove CleanMyMac.

http://macpaw.com/support/cleanmymac/knowledgebase/how-to-uninstall-cleanmymac-3

RAM

Upgrading RAM to 8GB will help.

http://eshop.macsales.com/shop/apple/memory/

When you see a beachball cursor or the slowness is especially bad, note the exact time: hour, minute, second.

These instructions must be carried out as an administrator. If you have only one user account, you are the administrator.

Launch the Console application in any of the following ways:

☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)

☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.

☞ Open LaunchPad and start typing the name.

The title of the Console window should be All Messages. If it isn't, select

SYSTEM LOG QUERIES ▹ All Messages

from the log list on the left. If you don't see that list, select

View ▹ Show Log List

from the menu bar at the top of the screen.

Each message in the log begins with the date and time when it was entered. Scroll back to the time you noted above.

Select the messages entered from then until the end of the episode, or until they start to repeat, whichever comes first.

Copy the messages to the Clipboard by pressing the key combination command-C. Paste into a reply to this message by pressing command-V.

The log contains a vast amount of information, almost all of it useless for solving any particular problem. When posting a log extract, be selective. A few dozen lines are almost always more than enough.

Please don't indiscriminately dump thousands of lines from the log into this discussion.

Please don't post screenshots of log messages—post the text.

Some private information, such as your name, may appear in the log. Anonymize before posting.

When you post the log extract, you might see an error message on the web page: "You have included content in your post that is not permitted," or "The message contains invalid characters." That's a bug in the forum software. Please post the text on Pastebin, then post a link here to the page you created.

As dominic23 pointed out, you've got adware installed.

In addition to that, you've got some other junk installed. CleanMyMac is very bad, and all such "cleaning" tools are completely unnecessary. Remove it. It's possible that you may have already removed it, but did so improperly, leaving behind some bits and pieces.

You also have µTorrent. Not only is downloading from torrents a very dangerous thing to be doing these days, but µTorrent itself is what has infected you with adware. Get rid of it, and never use another torrent app again.

Finally, it looks like your computer is in the middle of enabling or disabling FileVault. Although you can use your computer while this is happening, it will slow things down a bit. I'd recommend that you leave your Mac running unattended for a while, plugged in and without allowing it to go to sleep, so that it can finish the process as quickly as possible.

1. Back up your Mac if you have not done so already. To learn how to use Time Machine read Mac Basics: Time Machine backs up your Mac - Apple Support.
2. You inadvertently installed adware. You do not need to download or install anything to fix it.

   For a description of how this may have occurred, how to avoid it in the future, and for Apple's recommended actions read How to install adware. Apple's instructions are linked in the Recovery Procedure near the end of that document. Read and follow them carefully. Pay particular attention to the easily overlooked passages directing you to restart your Mac when required.

3. Google products including Google Chrome run poorly on Macs. Google has yet to demonstrate the ability or apparent desire to develop efficient OS X apps. If you are required to use Google products expect the need to upgrade your hardware frequently.
4. Greater exposure to potential malware intrusion will result from using a torrent client.
5. To remove CleanMyMac 3 itself, use its Uninstaller module, followed by these additional steps:

Remove the file ~/Library/LaunchAgents/com.macpaw.CleanMyMac3.Scheduler.plist

• To navigate to that file, copy and paste the following line into the Finder's Go menu > Go To Folder...

~/Library/LaunchAgents/

com.macpaw.CleanMyMac3.Scheduler.plist

• Then, open  (Apple menu) > System Preferences > Users & Groups > Login Items.
• Select the item CleanMyMac3 Menu
• Click the [—] (minus) button.
• Restart your Mac.

Beware that reinstalling OS X alone will have no effect on either removing CleanMyMac or reversing the damage it is capable of inflicting upon a system. To recover from the effects of having used it to modify OS X, the additional software you require and the essential files you may need follow the applicable recovery procedure below:

• If you have a backup that you created prior to using CleanMyMac, now is the time to use it. For Time Machine, boot OS X Recovery, and at the Mac OS X Utilities screen, choose Restore from Time Machine Backup. Choose a date preceding the installation of CleanMyMac.
• If you do not have a backup that predates the use of CleanMyMac, create one now. To do that read Mac Basics: Time Machine backs up your Mac.
  • The recovery procedure will require that you erase the Mac using OS X Recovery, and then create a new user whose contents will be empty. You will then be able to use Setup Assistant to migrate your essential documents including photos, music, work products and other essential files.
  • When doing so, select only your previous User account and do not select "Applications", "Computer and Network Settings" or "Other files and folders". De-select those choices.
  • Subsequent to using Setup Assistant, you will need to reinstall the essential software you may require, once again remembering to install software only from their original sources, and omitting all non-essential software.
  • "Non-essential software" is a broad category that includes but is not limited to third party "cleaning", "maintenance", and "anti-virus" products.

To erase and install Yosemite read: OS X Yosemite: Erase and reinstall OS X

To migrate your essential documents read: OS X Yosemite: Transfer your info from a computer or storage device and follow the procedure under Transfer info from a Time Machine backup or other storage device.

"CleanMyMac" and "uTorrent" are most certainly not causing your problem.

The startup drive is failing, or there is some other internal hardware fault. Everything else is irrelevant.

Back up all data on the drive immediately if you don't already have a current backup. There are ways to back up a computer that isn't fully functional—ask if you need guidance.

Make a "Genius" appointment at an Apple Store, or go to another authorized service provider.

If privacy is a concern, erase the data partition(s) with the option to write zeros* (do this only if you have at least two complete, independent backups, and you know how to restore to an empty drive from any of them.) Don’t erase the recovery partition, if present.

Keeping your confidential data secure during hardware repair

Apple also recommends that you deauthorize a device in the iTunes Store before having it serviced.

*An SSD doesn't need to be zeroed.

The freezing problems I experienced in Yosemite, was a mix of Flash and Firefox. I uninstalled all of them completely and the problem was fixed.