Hardware Upgrade to fix low FPS?

Hi guys, while playing DOTA 2 (on lowest settings), I am experiencing the problem that my FPS is down to 30 almost all of the time. This started about a month ago and is really annoying to me, which is why I decided to updgrade my hardware in order to fix this problem. Now I am facing the problem though that I have no idea which parts of my hardware cause the low performance and thus need to be exchanged, some help would be very much appreciated.

I have the Medion Erazer X6817 with the following hardware:
  • CPU: Intel Core i7-2670QM @ 2.20 GHz
  • Graphics Card: NVIDIA GeForce GTX 560M
  • RAM: 4GB DDR3
  • OS: Windows 7 Home Premium, 64 Bit
Some Additional Facts:
  • I use a LG 24MPHQ Monitor to display the game at 1920x1080 resolution
  • When playing RAM usage is constantly at about 3,2 GB, CPU Usage pending between 15 and 45
So what part of my notebook do I have to upgrade to improve my FPS?
 
If you can upgrade your RAM to 8 gigs that might help; it seems to be the sweet spot for gaming. Otherwise Dota 2 is not that demanding on hardware.

As one who is experiencing League of Legends disconnects I have found through the help of jobeard and Rage_3K_Moiz that it probably has to do with my internet connection. Here are 2 that I ran (both are safe) to check for Packet Loss:

http://netalyzr.icsi.berkeley.edu/
http://www.dslreports.com/pingtest
 
Back