Lag when playing Dota with Garena

I was using Windows XP before this, I can play the game on Garena smoothly with Windows XP.

After I installed Windows 7, problem started to occur. I lag a lot when playing LAN(Garena) with other players. I checked my latency and internet connection, my ping is just not much difference when I was playing with Windows XP last time and my internet speed is fine too. I don't think the problem is related to my internet connection, but the strange thing is that I can play the game with no lag when I'm playing single player! I know this sound ironic but I'm really experiencing this problem.

I'm using a D-link DIR-615 router that connected to my PC and below is my computer spec.

MSI/MS-7309
Windows 7 Home Premium 32bit
AMD Sempron(tm) Processor 2800+ 1607 Mhz
MSI K9N6PGM2-V2 (MS-7309)
1.50 GB RAM
Radeon X300/X550/X1050 Series Graphic Card

CheeseCake said:

I was using Windows XP before this, I can play the game on Garena smoothly with Windows XP.

Windows 7 Home Premium 32bit
AMD Sempron(tm) Processor 2800+ 1607 Mhz
1.50 GB RAM
Radeon X300/X550/X1050 Series Graphic Card

Running Windows 7 on an AMD Sempron, 1,5 GB RAM and with a Radeon X300/X550/X1050 grapics card is really not a good idea. Windows 7 is slower than Windows XP, especially with single core processors. Also your grapics card is very weak.

If you can, i suggest you to re-install Windows XP on your computer. Windows 7 is too much for your PC, and it causes all to lag.

Try solving multiplayer lag changing game's Windows compatibility mode, or disabling firewall and setting your anti-virus in "game mode" or something like that.