Ways to help make a slow Mac faster
17 Reasons Why Your Mac Runs Slower Than it Should
Slow Mac Performance? This Article Solves It!
Fix slow start-ups in OS X | MacFixIt - CNET Reviews
6 Easy Tips to Speed Up OS X Yosemite on Your Mac
Avoid using any third-party software that claims to clean up your computer. Usually this software does more bad than good. Furthermore, you don't need it. Note that all computers will become slower over time even under normal use. Experienced users typically erase the hard drive and do a clean install from scratch at least once a year or whenever installing a major OS upgrade. Of course doing so also means you must maintain regular and multiple backups.
Clearly, if you have installed malware like MacKeeper then you need to uninstall it. Other things to think about are adding more RAM, cutting back on the amount of third-party software you are concurrently running, and thinking about just erasing your drive and reinstalling all from scratch. You might also think about downgrading to Snow Leopard or upgrading to Mountain Lion. Lion is not a good selection to stick with.
How to manually remove MacKeeper from your Mac
Helpful Links Regarding Malware Problems
If you are having an immediate problem with ads popping up see The Safe Mac » Adware Removal Guide, remove adware that displays pop-up ads and graphics on your Mac, and AdwareMedic. If you require anti-virus protection Thomas Reed recommends using ClamXAV. (Thank you to Thomas Reed for this recommendation.) You might consider adding this Safari extensions: Adblock Plus 1.8.9.
Open Safari, select Preferences from the Safari menu. Click on Extensions icon in the toolbar. Disable all Extensions. If this stops your problem, then re-enable them one by one until the problem returns. Now remove that extension as it is causing the problem.
The following comes from user stevejobsfan0123. I have made minor changes to adapt to this presentation.
Fix Some Browser Pop-ups That Take Over Safari.
Common pop-ups include a message saying the government has seized your computer and you must pay to have it released (often called "Moneypak"), or a phony message saying that your computer has been infected, and you need to call a tech support number (sometimes claiming to be Apple) to get it resolved. First, understand that these pop-ups are not caused by a virus and your computer has not been affected. This "hijack" is limited to your web browser. Also understand that these messages are scams, so do not pay any money, call the listed number, or provide any personal information. This article will outline the solution to dismiss the pop-up.
Quit Safari
Usually, these pop-ups will not go away by either clicking "OK" or "Cancel." Furthermore, several menus in the menu bar may become disabled and show in gray, including the option to quit Safari. You will likely have to force quit Safari. To do this, press Command + option + esc, select Safari, and press Force Quit.
Relaunch Safari
If you relaunch Safari, the page will reopen. To prevent this from happening, hold down the 'Shift' key while opening Safari. This will prevent windows from the last time Safari was running from reopening.
This will not work in all cases. The shift key must be held at the right time, and in some cases, even if done correctly, the window reappears. In these circumstances, after force quitting Safari, turn off Wi-Fi or disconnect Ethernet, depending on how you connect to the Internet. Then relaunch Safari normally. It will try to reload the malicious webpage, but without a connection, it won't be able to. Navigate away from that page by entering a different URL, i.e. www.apple.com, and trying to load it. Now you can reconnect to the Internet, and the page you entered will appear rather than the malicious one.
Clean Install of Snow Leopard
Be sure to make a backup first because the following procedure will erase
the drive and everything on it.
1. Boot the computer using the Snow Leopard Installer Disc or the Disc 1 that came
with your computer. Insert the disc into the optical drive and restart the computer.
After the chime press and hold down the "C" key. Release the key when you see
a small spinning gear appear below the dark gray Apple logo.
2. After the installer loads select your language and click on the Continue
button. When the menu bar appears select Disk Utility from the Utilities menu.
After DU loads select the hard drive entry from the left side list (mfgr.'s ID and drive
size.) Click on the Partition tab in the DU main window. Set the number of
partitions to one (1) from the Partitions drop down menu, click on Options button
and select GUID, click on OK, then set the format type to MacOS Extended
(Journaled, if supported), then click on the Apply button.
3. When the formatting has completed quit DU and return to the installer. Proceed
with the OS X installation and follow the directions included with the installer.
4. When the installation has completed your computer will Restart into the Setup
Assistant. After you finish Setup Assistant will complete the installation after which
you will be running a fresh install of OS X. You can now begin the update process
by opening Software Update and installing all recommended updates to bring your
installation current.
Download and install Mac OS X 10.6.8 Update Combo v1.1.
Upgrading to Mountain Lion
To upgrade to Mountain Lion you must have Snow Leopard 10.6.8 or Lion installed. Purchase a redemption code at the Online Apple Store: OS X Mountain Lion. Mountain Lion is $19.99 plus tax. Use the code to redeem a download of Mountain Lion from the App Store. The file is quite large, over 4 GBs, so allow some time to download. It would be preferable to use Ethernet because it is nearly four times faster than wireless.
OS X Mountain Lion - System Requirements
Macs that can be upgraded to OS X Mountain Lion
1. iMac (Mid 2007 or newer) - Model Identifier 7,1 or later.
2. MacBook (Late 2008 Aluminum, or Early 2009 or newer) - Model
Identifier 5,1 or later.
3. MacBook Pro (Mid/Late 2007 or newer) - Model Identifier 3,1 or later.
4. MacBook Air (Late 2008 or newer) - Model Identifier 2,1 or later.
5. Mac mini (Early 2009 or newer) - Model Identifier 3,1 or later.
6. Mac Pro (Early 2008 or newer) - Model Identifier 3,1 or later.
7. Xserve (Early 2009) - Model Identifier 3,1 or later.
To find the model identifier open System Profiler in the Utilities folder. It's displayed in the panel on the right.
Are my applications compatible?
See App Compatibility Table - RoaringApps.