bubu_bubu :
Hello! I bought an ASUS G46 gaming laptop with a GTX 660M, an i5 and 4 gb ram. The only game that I has problems with was Assassin Creed 4 Black Flag (mostly because of all the vegetation). I'm planing on buying The Witcher 3 later this year, which also has a huge open world. Should I add another 2 gb (or 4) of ram? Does ram help with open world games?
Actually, that problem sounds like a slower video card... unable to handle all the polygons. Laptops have video cards that are slower than desktops, and this particular issue you are describing sounds exactly like the video card is having trouble handling certain scenes.
RAM will not help this problem. However, if you want to find out if some of your games could use more RAM, then keep an eye on how much RAM your system is using during the games to see if you are getting close to using all of your RAM.
Also, you are running the 64-bit version of Windows 8, right?