(I know the answer to this question. Posting this just to share the answer with the community)
My local (Windows 7) instance of Apache 2.4 experiences delays or hang-ups when serving some URLs, depending on which browser I use to access these URLs.
With Firefox/Chrome, Apache is slow to respond on certain URLs. The sluggishness occurs about 20% of the time on any given URL. When it does occur, there's a 5-second delay during which Firefox displays a "Waiting for..." status.
With Internet Explorer 9, Apache simply hangs and stops serving any requests (with any browser) until it is restarted.
- This seems to occur only with dynamic (PHP) requests, but not all of them. In fact, it only occurs on one specific site. Other PHP-based sites on the same machine work fine.
- It may or may not be significant that the problematic site consists of a large number of subdomains (VirtualHosts).
- Disabling the Windows Firewall and Comodo Firewall doesn't help.
- The problem seems more frequent with "busier" pages (additional requests for IFRAMES etc.)
I've tried many changes to
httpd.conf (such as disabling KeepAlive, EnableMMAP, HostnameLookups) but nothing seems to work.