Knight is asking the right questions. For specific advice, we would need to know those answers.
What I can offer is some general advice based on what you have posted so far.
DSL is generally reliable, but not really quick. Finding your upload and download speeds from someplace like
www.Speedtest.net would be useful. Those will be measured in Mega-bit-per-second, typically shortened to "M".
As an example, the service I pay for is 1.5M download and 0.3M upload. A "clean" connection for me runs at the full speed I pay for. Also, Mabi pushes the limits of my service, so I don't recommend slower connections. They will work, but the slower it goes the more problems you will see.
From your earlier post, it seems that you are taking all the best steps to optimize your connection already. (Don't mess with the MTU unless you have a static IP address and the network hardware to handle the upkeep on it.)
The other things that are possible include changing your startup config to bare-bones or using a secondary local login just for games. If you are not sure what to disable or how to reconfigure, then it's best not to do this. Disabling the wrong service can wreak havoc and make Mabi glitches look pleasant in comparison. Optimizing your computer will help it run programs, but it would not generally make it communicate to the net better.