If the spinning wheel bothers you too much and this began to happen these days, and not used to before, there are plenty of reasons for such.
Before thinking and spending bucks for upgrading any parts, look into some soft issues first.
Go to System Preferences, Users and Login Items. Remove all items from there. Restart your computer and see if that improved the spinning wheel behavior.
If not, reset your PRAM. In this case, turn off your computer, turn on, press Command, Option, P, R keys at the same time. When you hear another chime after you pressed those keys, release the keys and let it boot up normally.
If that didn't solve the issue of your spinning wheel, create a new Admin account and log in to that new Admin account and see if you observe the same spinning wheel behavior.
After attempting these soft solutions, if still the same issue persists, upgrade your RAM. That should improve speed performance slightly by decreasing the spinning wheel behavior. Enjoy!