Excessive wait time on Mage_Core_Block_Template::fetchView on /cms/index/index

Question

I'm investigating why our homepage wait time is so slow (4.8s). Using NewRelic I've found out that the Mage_Core_Block_Template::fetchView call is using an excessive 2800ms. I don't understand why it takes so long for it to fetch views while the Block Cache is active and that the Redis Server behind is working.

I'm using PHP 5.5 with PHP-FPM, Nginx, Redis and Percona MySQL 5.6.

Has anyone some clue on how to debug this weird behavior? This is the only page to do this, all the others requires under than 1.5s to render.