Eu literalmente descobri isso há alguns minutos: link . Você cola nos resultados de seu EXPLAIN ANALYZE e mostra onde pode haver problemas (é até codificado por cores).
Da seção de ajuda ...
explain.depesz.com is tool for finding real cause for slow queries. Generally, one would use EXPLAIN ANALYZE query; and read the output. The problem is that not all parts of the output are easily understandable by anybody, and it's not always obvious whether node that executes in 17.3ms is faster or slower than the one that runs in 100ms - given the fact that the first one is executed 7 times. To use the site, simply go to its first page and paste there explain analyze output from your psql. This output could look like this. After uploading you will be directed to page which shows parsed, and nicely (well, at least nice for me :) colorized to put emphasis on important parts. This could look like this. Side note: the url for colorized output is persistent, so you can simply use it to show it to others - for example - for those nice guys on irc channel #postgresql on freenode. This graph uses 4 colours to mark important things: white background - everything is fine yellow background - given node is worrying brown background - given node is more worrying red background - given node is very worrying Which color is used, is choosen based on which mode you will use: "Exclusive", "Inclusive" or "Rows X".