WAMP is slow to respond

When I access any virtual host while installing wamp, the browser freezes for about 4-5 seconds. After months of working with this problem, I found that the only way to fix it was to run ipconfig / flushdns. This seems to be a temporary solution that works sometimes.

What's really weird (and reproducible) is that as soon as I access the page, although the vhost, after it hangs for 4-5 seconds, it responds pretty quickly every time after the first. But if I leave the browser for about 1-2 minutes and then go back to refresh the page, it hangs again for 4-5 seconds. It's almost the same as Apache dumping something every time I wait a minute or two between requests.

Has anyone else experienced something similar?