Laptop running games slow

I'm curious to know why this Acer aspired v3-551 runs games slow. Like Street fighter X Tekken can't run at max. Iron brigade, or even this MMO I play being FFXI (I get lag running everything on high)

Specs AMD Quad core processor A84500
AMD Radeon HD 7640g 512 MB
4GB DDR3
500 GB HDD

I play FFXI a lot and I can't even increase resolution a bit or some settings higher because I will begin to experience some lag "moving game camera slower then normal speed" is there a particular reason as to why this laptop is having problems with light weight games?
I have only updated GPU driver and replaced HDD with SSD (ive notice no improvements for any game other then pc booting in 5 seconds, and everything else OS wise is insane fast" I'm being told that if I update ram to gaming/better ram my experience will increase? Because this stock ram "sucks" so I'm looking at 8 GB 1600 HMZ, should I buy that, will it even help me, is stock ram from laptops in general just bad?

It's a mobile low-end APU. You don't actually have a graphics card.

You need to turn down the graphical details in games.

RAM won't help you much, 4GB is OK.

I had ordered Corsair Vengeance 8GB (2x4GB) DDR3 1600 MHz and arrived today. I'm glad I went along and did. I ran previously ran FFXIV RRB and scored 2087 and now with new ram scored 3655. So ram did help me. Thanks I can run previous games I mention on high smoothly. Thanks for information though.

When it comes to the on-die GPU for APUs you'll notice an increase is performance when to comes to RAM speeds. They did an article on Tomshardware.

Link---> http://www.tomshardware.com/reviews/memory-bandwidth-scaling-trinity,3419-3.html

Yeah since the memory is shared it helps.
P4PC
1) Use this utility to uninstall old drivers: http://sites.amd.com/us/game/downloads/Pages/catalyst-uninstall-utility.aspx
2) Install new drivers from here:http://support.amd.com/us/gpudownload/windows/Pages/radeonmob_win7-64.aspx
This should further help in improving game performance.