I have a file server running Windows 7 and a client connecting to it running Windows 7, too. They're connected by a private Gbit LAN connection. After starting the server, my client connects to it flawlessly and very fast. VNC connects instantly and mirrors the server's screen nearly realtime. When I access several programs which provide a web server via python, the connection is very fast too.
But after a while (some days of uptime), the connection gets slower. Connecting via VNC takes seconds, the refresh of VNC sometimes takes 2 or 3 seconds. RDP is the same. The initial loading of the website provided by the programs takes very long too, but once it's loaded it works fine. But copying files works with 30 or 40Mb/s, so the reaction time is slow, not the throughput.
I used to have Windows Server 2008 running, but because I had this problem I installed Windows 7 on the server, which did not help. I uninstalled Comodo Firewall because I thought it could be the source of the problem. I connected to the server using a public network which both are connected to (with different network cards) and the problem is the same. I did not find any programs filling the memory or such, there are only about three or four running an any time, apart from the usual services.
So basically the problem exists with different OS installations and different network cards.
Any ideas what might be wrong here?