I was developing some managed UDP interfaces on Windows 7 and was trying to debug this problem and ultimately determined that it occurs in unmanaged code also. The unmanaged code has been used for years without trouble on Windows XP. The problem is that when I create a UDP packet (port 7000) that echos all received data (1000 packets/sec) to the network to test CPU usage, there is a CPU spike every 10-15 senconds that goes up to 50% of the CPU for less than a second. The rest of the time (for about 13 seconds) the CPU is close to 0% usage. The packets are always echoed as expected with very low latency (milliseconds) even during the CPU spike. In other words there is no noticeable problem other than the CPU spike. I have tried turning off Windows Firewall, and Windows Defender without luck. There is no other virus or sniffing software running. The task manager reports the spike coming from the the UDP Echo application, and some in System.

Hi, It appears this issue is related to development, for this kind of issues, it is recommended that you go to our MSDN forum for help: Microsoft Developer Network Forums Home Thank you for your understanding and cooperation. Hope the issue will be resolved soon. Nicholas Li - MSFT