The latest PHP7.0 come with huge speed improvement. PHP7.0 debian package is available from dotdeb repository.

deb http://packages.dotdeb.org jessie all
deb-src http://packages.dotdeb.org jessie all

Then install the key

#wget https://www.dotdeb.org/dotdeb.gpg
#sudo apt-key add dotdeb.gpg
#aptitude install php7.0-fpm php7.0-pgsql php7.0-cli

Please note that some extension not yet available.

Related
PHP 7.0.3 for jessie
Dotdeb install instruction