Hello,
Firstly, you can use any kind of laptop with expandable RAM, so you can buy and insert your own RAM to increase your laptop speed. Most of laptops have 2 slots of RAM, so you can remove the old 1 GB RAM for example, and replace it with two 2 GB RAM (2 GB + 2GB = 4 GB), it would be more than a 5 star machine. Or you can have your current 1 GB RAM and buy another 1 GB RAM (1 GB + 1 GB = 2GB).
Secondly, if you want to play your game without lags during the 3D match, you have to get a laptop with good video card, at least 1 GB of video card. Please note that video card inside the laptop is not replaceable.
RAM is the card that boost your computer speed, Video Card is the card that enhance your graphics.
Might help you, thanks.