Same here with PHP 5.6.12
'./configure' '--prefix=/opt/php-5.6.12' '--with-pdo-pgsql' '--with-zlib-dir' '--with-freetype-dir' '--enable-mbstring' '--with-libxml-dir=/usr' '--enable-soap' '--enable-calendar' '--with-curl' '--with-mcrypt' '--with-pgsql' '--disable-rpath' '--enable-inline-optimization' '--with-bz2' '--with-zlib' '--enable-sockets' '--enable-sysvsem' '--enable-sysvshm' '--enable-pcntl' '--enable-mbregex' '--with-mhash' '--enable-zip' '--with-pcre-regex' '--with-mysql' '--with-pdo-mysql' '--with-mysqli' '--with-png-dir=/usr' '--enable-gd-native-ttf' '--with-openssl' '--with-fpm-user=www-data' '--with-fpm-group=www-data' '--with-libdir=lib64' '--enable-ftp' '--with-kerberos' '--with-gettext' '--with-gd' '--with-jpeg-dir=/usr/lib/' '--enable-intl' '--enable-fpm'
NGINX php-pfm
Phalcon 2.0.6
Linux Ubuntu-1204-precise-64-minimal 3.8.0-42-generic #63~precise1-Ubuntu SMP Fri Jul 4 21:16:26 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
Keep getting random errors and bad gateway as well.