Activity monitor will show you how much Physical Memory vs how much you are using. Mine was equipped with 4 GB new, with 2 chips, 2 slots open. I could see just at start-up I was using up all my memory. 3.99 out of 4.00GB.
5 minutes. No problems. Moved the unit to the edge of the desk. Removed 3 screws, pulled back two plastic sheet tabs, pushed in two extra RAM chip. Reassemble & power back up. Repair does not get easier than this. Now I run from about 4.50 GB used to around 7.50 GB used out of 12 GB; even with many programs open. Smooth sailing.
It was so easy and inexpensive to triple the RAM in my machine. Took 5 minutes & no more beach balling.