We recently upgraded from Confluence 5.1.4 to 5.4.3 and now some of our more complex pages and templates are broken. We've isolated the issue down to the number of sub-nested macros. To recreate the issue do the following:

Create a page with 35 Info macros on after another = no problem
Create a page with 35 info macros continually nested inside of each other and the page will timeout after 2 minutes trying to save. (Page not found error).

I chose the info macro because it is a very basic Atlassian macro however I've reproduced this with a variety of different macros.