My 20M network speed is very slow in opensue 13.1

Dear friends:
I use 20M network. but it only give 256K speed in the opensuse 13.1 system.
I use the firfox and google chrome.
The network has a speed of 2.4M in the windows system on the same computer.
Could you please give me some advice for that.

Like most distros, openSUSE (actually mainstream kernel settings) are by default very conservative to support relatively old, small and limited resource hardware. When you’re talking about a very fast Internet connection, you need to implement changes that enable gulping faster and larger chunks of network data at a time.

I discuss and describe optimization changes you can make for an earlier version of openSUSE but they all apply just as much today to current running openSUSE.

Recommend you look closely at modifying the TCP/IP Congestion Control algorithm and enlarging TCP/IP network buffers, possibly enlarging TCP/IP windows, more. You might consider in fact increasing even my suggested settings changes considerably more than I state if you have sufficient RAM and depending on what else is running on your machine.