Question: my mac is running really slow how do i fix it?
Answer: Your computer's startup disk may not have enough free disk space. ... 
An app you're using may require more memory than your Mac has easily available. ... 
Quit any app that isn't compatible with your Mac. ... 
Quit any apps you're not using.
If you have problems with your disk, use Disk Utility to verify and try to fix any issues.