1 - How to Force Quit Applications on Your Mac When They're Not Responding 

Macs are very stable, but not every Mac application is. Every once in a while, something you’re using is going to crash. Sometimes this means the spinning beach ball of death, sometimes this means clicking an open window doesn’t do anything, no matter what you try. Sometimes the Dock indicates an application is open, but you can’t seem to find or open any windows. Whatever’s gone wrong, clicking the red button or pressing Command+Q isn’t going to cut it. Here’s how to force zombie applications to quit, so you can re-launch them in a working state. Use Command+Option+Esc 

2 - Find Resource-Hungry Processes

Use the Activity Monitor — sort of like the Task Manager on Windows — to view your running processes and find ones devouring too many resources. 

 To launch it, press Command+Space to open Spotlight search, type Activity Monitor, and press Enter. Or tell Siri to open the Activity Monitor. 

Click the “% CPU” heading to sort by CPU usage and see the running applications and processes using the most CPU. In some cases, there may be a single runaway application using 99% CPU that you’ll want to end. To force-quit a process, select it by clicking it and click the X button on the toolbar. Be sure you aren’t quitting a process that’s doing something important. You can always try to close a resource-hungry app in the normal way first. Command+Option+Esc 

If this isn’t working, click the “View” menu and select “All Processes” to see all the processes running on your Mac. You can also click over to the Memory section — a process using a large amount of memory could cause your Mac to slow down. Try the “Disk” section, too — a process using the disk heavily could also be causing your Mac to slow down.

Learn more about the various processes found in Activity Monitor, like hidd, mdsworker, installd, and many others. Don’t know what those services are? Better start reading!

3 - Close Applications

Mac OS X likes to leave applications running in the dock. Even clicking the red “X” button on an application window won’t close it — it’ll remain running in the background. In most cases, this isn’t a big problem. However, if your Mac appears to be running slowly, you may want to close some of these applications.

Look for the applications marked with a dot on your dock, right-click or Ctrl-click their icons, and select “Quit.”

4- Prune Startup Programs

If your Mac is slow after you log in, it may have too many startup programs.

To manage startup programs, open the System Preferences window by clicking the Apple menu icon and selecting “System Preferences.” Click the “Users & groups” icon, select your current user account, and click “Login Items.” Uncheck any applications you don’t want starting when you log in.

If you ever want to make a program automatically start when you log into your Mac, drag-and-drop it into this list or click the “+” button at the bottom of the list and add it.

5 - Reduce Transparency and Animations

Transparency and animations can tax the graphics hardware on older Macs. Reducing them can help speed things up — it’s worth a shot.

To do this, open the System Preferences window. Click the “Accessibility” icon and check the “Reduce transparency” option to reduce transparencies. 

You might also want to click the “Dock” preferences icon and select “Scale effect” rather than “Genie effect,” which could speed up the window-minimizing animation a bit.

6 - Lighten Your Web Browser

Your web browser might just be the application causing your problem. The usual tips apply on a Mac, too — especially considering Google Chrome’s performance is particularly bad on Mac OS X.

Try to minimize the number of browser extensions you use and have fewer tabs open at once to save memory and CPU resources.

You might also want to try the Safari browser included with Mac OS X, which does seem to perform better than Chrome — especially when it comes to battery power. If you can get away with using Safari and aren’t depending on a feature or extension in Chrome, for example, you might want to give it a serious try.

7 - Speed Up the Finder

When you open the Finder window to view your files, it opens to an “All My Files” view by default. If you have a very large number of files on your Mac, this view might be slow to load, slowing FInder down every time you open a new Finder window.

You can prevent this from happening by clicking the “Finder” menu and selecting “Preferences” in Finder. Select your preferred folder under “New Finder Windows Show” — for example, you can have all Finder windows automatically open to your Downloads folder. Finder won’t load the All My Files view anymore.

8 - Free Up Disk Space

As on any computer, freeing up disk space can also speed things up if you have a very small amount of disk space. To check, click the Apple menu, select “About This Mac,” and look under the “Storage” heading.

If there isn’t a decent chunk of free space, you’ll want to free up space on your Mac’s internal storage.

10 Ways To Free Up Disk Space on Your Mac Hard Drive

9 - Reset Your SMC to Fix All Sorts of Problems

This useful tip that can fix a wide variety of system problems on a Mac, although many people — especially experienced Windows users — wouldn’t think to try this. Resetting the System Management Controller — or SMC — can fix everything from slow performance to startup issues and Wi-Fi hardware problems. This won’t actually erase any data — it’s like performing a lower-level reboot of your Mac.

Follow the instructions in this article to reset your Mac’s SMC.

10 - Reinstall Mac OS X

This should only be done by you if it is your personal device and not a school device.

When all else fails, try reinstalling your operating system. This is a good tip for every device — it’s even a good idea if you’re having a problem with an iPhone or iPad.