Hepl! Having troubles with FPS of my w3

[:1]Hey there!! This is my first post... Before I say something let me say sorry about my English xD

Well yes i've been having problems with my warcraft... what happens is that when I play (DotA-Allstars) it's kinda PC-lag, first i thought that maybe was my internet but i used a friends PC on my home and it was nice with 60fps... So I figured that it's not my internet.

So that leaved my just the option that yes its PC lag... but i had an older PC that happen the same but that was a piece of ****. but now i have a much better PC... let me give you more info about my laptop

* 2.3GHz AMD Turion II Dual-Core Mobile M520 Processor

* 4GB 200-Pin DDR2 SO-DIMM Memory

* 320GB Serial ATA Hard Disk Drive (5400RPM); DVD SuperMulti Drive with Labelflash

* 17.3" LED (16:9) 1600x900 Display; ATI Radeon HD 4200 Graphics

* Window 7 Home Premium 64-bit

I'm also ussing 1.24c/d/e

i use a Version switcher to be between those versions but (i don't think the switcher it's the reason of the lag since i have friends that use it

Please help me... Why's that happening?

Thanks for reading

Amazon Link of my Laptop [just in case you wanna look up futher (?)]:

http://www.amazon.com/gp/product/B00...ES0KD9GV29S6W0