I know a few of you people support businesses which run SAM/Orion for accounting for automotive businesses.

Ive come across an issue a couple of times, where if the network is mixed XP & 7 then the program takes a large performance hit.

First time it was a new client machine being the first windows 7 machine on their network. Orion took 2 minutes to load up the account transactions screen. Other XP clients took about 5-10 seconds.

I spent a long time troubleshooting this & talked directly to sam who suggested throwing more money at it(gigabit switches, more new machines etc), without any type of fix. (NOTE I tried a gigabit switch and it halved the load times, but still took 2-5x longer than the pure xp-xp network at 100mbps)

Now Ive seen another business using SAM (only two computers) and the file server got stuffed and has been replaced with a new windows 7 machine. Now the same thing has happened, the xp client machine is now far slower than before.

Things I've tried...

Turn ethernet adapter from auto negotiate to half duplex - following another thread on slow xp 7 speed issues
Turn off  tcp global autotuning
Turn off Large Send Offload v2 (IPv4) & Large Send Offload v2 (IPv6)
Turn off homegroup
Uninstall antivirus (NOD32)  & disable windows defender
Disable SMB2
Downgrade NTLM Authentication to v1
Turn off ethernet adapter flow control

A little note about the their setup. It is two computers, connected via ethernet to an all-in-one adsl router.

Any tips on how to fix this network issue between windows 7 & XP? Someone must have come across this before. Simply accepting that new hardware to 2-10x slower than the old hardware is tough.