Reset the NVRAM & PRAM

• Shut down your Mac.
• Turn it on and immediately press and hold these four keys together: Option, Command, P, and R.
• You can release the keys after about 20 seconds, during which your Mac might appear to restart.

Reset the SMC

• Shut down your Mac.
• Turn it on and immediately press and hold these four keys together: Shift, Control and Option, then press the power button at the same time.
• Hold these keys and the power button for 10 seconds and then release them. In case you have a MacBook Pro with Touch ID, the Touch ID button is also the power button.
• Restart your MacBook pressing the power button.

Clean the system cache

• Remove files from ~/Library/Caches folder