Do you have room left on your startup disk?, generally anything below 5% of the total size is substandard, empty your trash/secure empty trash as this will remove deeper hidden files in the trash and often helps to speed things up, you could also try a pram reset, i’ve cut and pasted the following procedure from another mac helpdesk
You can also run a PRAM Reset, which which can refresh the firmware software of your processor and memory. Don’t recommend doing this all the time, however, if you are experiencing a lag in performance, this is a great procedure to implement.
Here is the process:
Here are some steps you can try to resolve the issue:
• First, hold in your power button for approximately 10 seconds to do a hard shutdown.
• Once your Mac is shutdown, you will need to perform what is called a PRAM reset (Parameter RAM)
• Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously .
• Turn on the computer.
• Press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears.
• Now, hold the keys down until the computer restarts and you hear the startup sound for the third time.
• Release the keys and allow the Mac to start up. You should experience better performance of your Mac after running this procedure.
Whatever you do please do not use a program called mackeeper under any circumstances, it’s a scam program that does ****-all good.
