Early 2013 Macbook Pro problems!

[Vyrtorion]

Processor: 2.4GHz Intel Core i7
Memory: 8GB
Software: OSX 10.9.4

My Mac is freezing. I thought it was because I had barely any space left on it so I got rid of a bunch of stuff and now have more than half the storage empty. But that didn't help. What happens when it freezes (and I find it does it a lot when I have more than two different apps open at the same time) is the fans suddenly start blowing really loud, even if the laptop isn't hot to touch, and then the mouse or keyboard becomes unresponsive or really slow. Apps stop responding, things stop downloading.. Then the cursor turns into the little rainbow circle and nothing works except moving the mouse around. Sometimes it'll stop, the fans will slowly shut down and everything will unfreeze but most of the time I have to hold down the power button to restart. It is really really frustrating because I can never get anything done. It does this quite a few times a day.
I've restarted my laptop multiple times.
This has been going on for a while now..
Please help.

 

[r0k]

Processor: 2.4GHz Intel Core i7
Memory: 8GB
Software: OSX 10.9.4

My Mac is freezing. I thought it was because I had barely any space left on it so I got rid of a bunch of stuff and now have more than half the storage empty. But that didn't help. What happens when it freezes (and I find it does it a lot when I have more than two different apps open at the same time) is the fans suddenly start blowing really loud, even if the laptop isn't hot to touch, and then the mouse or keyboard becomes unresponsive or really slow. Apps stop responding, things stop downloading.. Then the cursor turns into the little rainbow circle and nothing works except moving the mouse around. Sometimes it'll stop, the fans will slowly shut down and everything will unfreeze but most of the time I have to hold down the power button to restart. It is really really frustrating because I can never get anything done. It does this quite a few times a day.
I've restarted my laptop multiple times.
This has been going on for a while now..
Please help.

If this were happening to me, I'd create a new user and log in as the new user and see if it's still laggy. if it's laggy as a fresh new user, I'd do a reinstall. I assume you have everything backed up, right? RIGHT? Boot to the recovery partition and pick reinstall OSX. By default it reinstalls the OS and leaves all your data and apps there.