Since upgrading to WP3.6, W3 and Code Insert Manager won't work well together.
If i disable Minify, Database, Object and Browser caching, the problem goes away.
Sometimes I get this error:
Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0
Sometimes the page shows a blank page, without any error, without any content.
I've checked my host, it allows 256MB memory_limit for PHP.
I've set my php.ini to limit to 128MB like this in PHP.ini:
memory_limit = 128M ; Maximum amount of memory a script may consume (128MB)
I´ve set the wp-config.php to:
/** Increase memory limit for php to 128MB. */ define('WP_MAX_MEMORY_LIMIT', '128M');
I´ve optimized my DB, it's 14.076 MB now.