ASP.net site on IIS7 – intermittently very slow on all remote connections, but always very fast locally

asp.netiis-7performance

One of our asp.net sites is intermittently very slow when accessed from the Internet. But even when very slow remotely, it is still running very quickly when accessed on Remote Desktop from the server itself.

This isn't a client problem – I've RDC'd from multiple locations and it is always slow from every location, whilst being fast locally.

This only affects ONE site. All other ASPNET sites on the same IIS server still run quickly remotely and locally! So It's hard to diagnose a network issue.

20 mins later everything will go back to normal. Until the next time.

Any thoughts?
Thanks

Best Answer

You have a bottleneck "upstream"of you that appears to be specific to the path used to get from the customers to you.

Start with a client machine and work toward your server, checking each step in the path. Use something like firebug to see how long a apecific typical query takes when it's running well, and do a traceroute from the client to the server, recording each time.

Then when it slows down, repeat the process you've practiced, carefully looking for anything that takes longer. This could be everything from a client router overload to a dns server to a load balancer to a firewall: literally every step on the way could be suffering an overload, and dragging down the performance of your service, an innocent bystander (:-))

--dave

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