Very slow transfer on large files while using Zend Server on localhost

Question

I'm running Zend Server 5.1.0 on localhost, combined with Zend Studio for development.

We're currently working on a project that includes ExtJS4, so the main lib file ext-all-debug.js gets loaded on every page in the project. This .js file is rather large - 2.3MB and takes about 90(!) seconds to load on my laptop. Needless to say it's really annoying to have to wait 2 minutes after every Ctrl+F5.

• This behaviour appears in FireFox, Chrome and IE, so it's not browser related.
• I don't think it's hardware related either; I'm running a Dell Latitude E6500 with a C2Duo (2.67Ghz), 4GB RAM and an Intel SSD as host disk for Zend Server (so I think it's safe to say we i/o issues can be eliminated, as everything else is fast & smooth on this machine).
• Host OS is Windows 7 professional (64-bit).
• The rest of Zend Server's performance is acceptable on the machine (loading a large Ext.Direct dataset via Doctrine and CodeIgniter takes about 6 seconds.. not the same performance as my PowerEdges, but fine for development).
• Furthermore, I can't imagine any network issues being in play, as it's all happening on localhost.

I can't find any throttle or shaping settings in Zend Server and I ran out of things that spring to mind that could be related to this problem. I have already tried these common sources of speed issues to no avail:

• HostnameLookups Off in httpd.conf (Only works for initial slowness, but I'm suffering during transfer)
• Access using 127.0.0.1 and/or ::1 instead of localhost, eliminating host resolution errors
• Disabling IPv6 in FireFox configuration
• Tracerouting to localhost or any of it's aliases gets me there in one hop, so there are no weird external routes.