For some reason on my XPSP2 computer, accessing localhost or loopback is slow, which accessing 127.0.0.1 OR an entry made in HOSTS pointing there is fast. It doesn't matter which program I use (Firefox, Internet Explorer, PuTTY all experience it) or port/protocol (tried Apache on several ports, and my IRC server).

I can't figure out why or find anything to help me fix it. It's getting annoying. Ideas?

[Edit: I tried disabling all network protocols in the network connection settings except TCP/IP. Didn't affect it.]

[Edit: It's not the firewall either.]

[Edit: Also this has happened for awhile, so a simple reboot or reconnect won't work. My computer name (phoenix) also has the slow behavior, although that resolves to my LAN IP instead. My LAN IP by itself is fast.]

Firstly, your hosts file should have an entry pointing localhost at 127.0.0.1 by default. That's the default hosts file, afaik.

I've had this issue (or something similar) pop up when I'm trying to access a web server on my local box via it's internet address, and I've always assumed it was caused by my router having a hernia over routing things from my box to my box or some such software kerfuffle.

Is this really an issue for you? Just pop an entry in your hosts and be done with it.

The entry IS there. Doesn't make a difference.

I don't think the problem is in DNS.

Also ICMP is unaffected, leading me to believe it's a TCP problem.

I wouldn't have thought it was TCP itself, as DNS should resolve "localhost" to the IP address "127.0.0.1" before it touches the TCP/IP layer, surely?

Edit: Perhaps this article might help?
http://support.microsoft.com/kb/316716

I run XP, not 2000 or NT.

Just for kicks did you flush your DNS?

This has occurred over months, between lots of reboots, so yes.

i blame your router/switch

Except it doesn't happen on Vista.

Plus localhost traffic never leaves the computer.