Graphic of MacBook Pro using too much RAM

Hi,

I have a MacBook Pro 15" Mid 2012, with the following specs:

Intel Core i7 2,3 Ghz

8 GB RAM 1600 MHz DDR3

Intel HD Graphics 4000

NVIDIA GeForce GT 650M 1GB RAM

When the mac is using the Intel Graphics, and run the Netflix and some YouTube tabs, booth on Safari, the Mac doesn't freeze, but after a few seconds it automatically change to the NVIDIA GeForce graphics, than start to slow down. I did a test where I had on Safari one tab on Netflix and 5 tabs on youtube simultaneously playing, the Mac freeze up, forcing me to do a hard reset.

I start facing this problems few weeks after the new Mac OS was release, but now it's getting worse.

When I play some games, then it is the worst, and the video settings in the games are at the lowest.

Is someone getting the same problem, or is my mac getting to old now? Or even bad, is Apple slowing down my Mac to "preserve" my battery?

Thanks in advance!