Yes, and very easy one.
Increase the memory that can be allocated to a PHP script.
This is done ususally in php.ini. Now seems you have there value 12M, so just increase that to 16M. (or more if needed)
(You need to restart webserver for this to take effect)
On some server configurations, this can also be done in .htaccess by using
php_value memory_limit 16M
directive, but please note the usage of
php_value directives in .haccess may be disallowed by the webserver configuration.
If you are not sure about this, consult this with your server administrator.
I'll give it a try, but why would it require more server memory to generate PDFs with JoomSEF enabled vs not enabled?