go to dslreports.com and read up on Rwin tweaking for your OS, that may help a wee bit.
Dr. TCP is a great utility to adjust things!
Jackmds(as usual) was also on the money for the MTU on router.
sometimes, there is nothing you an do.
I have an 8mb OOl cable connection that has been chopped down to 3.5Mb because of the Original Sonic Wall SOHO firewall I am using and nothing can change it.