aggressive cache

My company recently launched a channel on msn.com -- yes, MSN has gone (partly) Drupal (a little bit)!

http://fitbie.msn.com/

This is a LAMP, PF 6.19 app with Cache Router (6.x-1.0-rc1) and multiple memcached bins, sitting behind Akamai. The home page is constructed in Panels (6.x-3.7).

We've had troubling recurrences of 404 home page responses. The symptoms look like this:

1. We get monitoring alarms that the home page is serving up 404 responses.
2. Apache httpd logs indicate 404s.
3. Watchdog indicates nothing.
4. Loading from our origin server looks good.

If you're not a native English speaker doing Drupal, then the i18n module is probably the only way. This is why it seems very strange to me that the performance admin page says that i18n might not work with aggressive caching.

I find it hard to believe that multilingual drupal sites scale worst or harder than sites with one language.

scale worst/hard = scale without advanced caching

Is there anyone with experience using the i18n with aggressive caching?

This is a question that had been asked before and discussed elsewhere. For instance, https://wiki.fourkitchens.com/display/PF/Modules+that+break+caching%2C+a... provides a list of modules that break the external and aggressive caching - some of them does not play well with normal cache either.

I need Drupal for Facebook and Organic Groups, both of which are listed as incompatible when external cache setting in the performance page is enabled.