I measured the throughput of a locally bound TCP socket connection on my computer (Intel Q9550, 64 GB RAM, Windows XP 64 bit) using iperf. I got dissatisfying results (around 1.6 Gbit/s) each time, no matter how I tweaked the TCP settings (buffer length, window size, max segment size, no delay). I got similar results when I tried netperf.
Now, I understand (from sources like these) that the average throughput of a loopback connection should be around 5 Gbit/s. What could be the reasons for such poor performance?
Best Answer
Antivirus is the first thing I would blame, and note that includes AV-only not just ones that include a firewall. If CPU usage of AV is above normal you know it is the culprit.
Otherwise, have you tried jumbo frames? What device/driver is it?