In addtion to the above this will help too.
Download DrTCP: <a target=new class=ftalternatingbarlinklarge href="http://www.dslre
ports.com/front/DRTCP021.exe">http://www.dslreports.com/front/DRTCP021.exe</a>
Run the program, it will show the current settings of TCP/IP parameters. Write them down.
You can change any variable that you want, click Apply, and reboot the computer, if no good; you can always change to your original values.
Start with*:
MaxMTU - DSL =1492, Cable = 1500. DialUp = 576
Tcp Receive - 255552 (This is the varaible to play with!)
Window Scaling - Yes
Time Stamping - No
Selective Acks - Yes
Path MTU Discovery - Yes.
Black Hole - NO
Max Duplicate - 2
TTL - 64
*Notice it said above
Start with
These settings are not written in "stone" there is variability depending on the compute'sr other settings. So try few settings and measure your Download for each one.
If you have a Router, the Router's MTU, if set differently can affect the general MTU.
Link:
Measuring the "Speed" of Internet Connection.