Here's what I've done: I wrote a minimal web server (using Qt, but I don't think it's relevant here). I'm running it on a legal Windows 7 32-bit. The problem: If I make a request with Firefox, IE, Chrome or Safari it takes takes about one second before my server sees that there is a new connection to be accepted. Clues: Using other clients (wget, own test client that just opens a socket) than Firefox, IE, Chrome, Safari seeing the new connection is matter of milliseconds. I installed Apache and tried the clients mentioned above. Serving the request takes ~50ms as expected. The problem isn't reproducible when running Windows XP (or compiling and running the same code under Linux) The problem seems to present itself only when connecting to localhost. A friend connected over the Internet and serving the connection was a matter of milliseconds. Running the server in different ports has no effect on the 1 second latency Here's what I've tried without luck: Stopped the Windows Defender service Stopped the Windows Firewall service Any ideas? Is this some clever 'security feature' in Windows 7? Why isn't Apache affected? Why are only the browsers affected?