Win7 vs WinXP Download Speed Increased ?

[poolmon]

I installed Win7 64 bit OS in my existing computer which had Win XP 32 bit. My Comcast download speed immediately increased by 45% (from 15.5mb to 22.5mb). Upload speed remained the same at 10mb.

I just put together a second computer with Win 7 (to replace my back up that had also had Win XP) and got the same exact result in increased speed.

All computers were connected by wire to the same router/modem so that is not playing a part in this .

Can anyone tell me why my upload speeds are so much higher with Win7 vs Win XP?

 

[OldMX]

Because the TCPIP stack got a refresh and got tweaked for performance on Win Vista/7/8.

 

[poolmon]

Thanks.
Is there a way that I can refresh my older XP computer's stack (while it is disconnected from the router) and just reconnect it to see if it speeds up too? I don't want to attempt anything that would affect my network but I don't mind it if something unexpected happens to that older computer itself. I try to avoid anything that would affect my existing systems since I don't have the in-depth knowledge to fix network issues.. Thanks Again