How to reduce lag while playing games in Garena

The solution for that is half-open limit.

BTW what is half-open limit?

Windows XP SP2 and later versions have only limited 10 concurrent half-open outbound connections.
After 10, new connection attempts are put in a queue and forced to wait.
Thus, the speed of connection to other PCs is limited.
(Microsoft do this to slow the spread of virus and reduce DoS attack)

To simplify, it means when surf forums, you can only load up to 10 images at once.
If there's 20 images, you need to wait another 10 images to finish then only it load.
If torrent download, you can only receive connection up to 10 seeds.
If Garena, you play DotA already connecting to 9 players then anything like auto-update or download interrupt, surely it lag.

To solve this, simply change the value to 256.
256 is tweak for gaming and download. (Recommended Value)

Hope this will help you for better gaming experience.

Source: http://half-open.com/