I have been struggling with performance issues on my high traffic wordpress site for months. I have spent weeks tinkering with my installation and w3tc options.
I recently upgraded to WP 3.3 Beta to see if the /%category%/%postname%/ permalink structure I was using could be causing the performance issues I was seeing. I definitely noticed improvements, but I still would see occassional 4+ second TTFB (time-to-first-byte).
Running out of options, I moved servers from Rackspace cloud to WPEngine. They enabled object caching and that caused MAJOR performance issues (11k DB writes/request).
Is there known issues with large amounts of categories and/or Object Caching?? Any solution to this problem? I feel as if I've tried everything... came here as a last resort.
Any help/input would be greatly appreciated!