Nginx as Apache Reverse Proxy - Lightbox2 Server Handling

I recently had some time to experiment with nginx as a reverse proxy for Apache, and so far I'm very pleased with the results. A big thanks to Perusio for his configuration files; they were a great basis to start from.

The Drupal 6 instance I have on this particular service makes use of the Lightbox2 module for images only. I've discovered that this module is sending an AJAX request to system/lightbox2/filter-xss on every modal load to filter the caption, which is putting regular load on Apache for a relatively trivial task that I'd much rather have put on nginx. I was wondering whether anyone else running the same server setup noticed this behaviour before and has a fix.

I can think of a number of possible solutions:
1. Enable lightbox2 lite, which solves the issue at the cost of losing many of the features I want in the full lightbox2 module.
2. Hack the module javascript to eliminate this call.
3. Try a different lightbox2-like module, if one exists that doesn't make such a call (does anyone know off the top of their head if there is one?)
4. Let nginx handle everything including the PHP - for various reasons don't want to go there yet.