Q and A::Configuration settings impacting speed
When I looked at what they were in the past they didn't seem to be worth using. It IS currently a selection you can make with 2.5.7 as far as I know in the installation program but is removed in 2.6.0. You can always go back and toggle it on in your secure.php file as mentioned by Mamba.
When I converted Doctrine to work with Xoops for 2.6 the persistent connection stuff did not work and when I looked through the support forums for Doctrine it appeared that the PDO library has a much more efficient way of doing things so a persistent connection is not necessary and will actually prevent some functions of Doctrine to work if you try to use it so support for it is non existent for 2.6 but again it is not needed.
In short my understanding is that is creates a connection to the database that never gets closed. The intent is that the performance is boosted with this because you do not need to keep opening and closing the connection. My understanding is that in reality it creates little if any actual performance boost and because you are opening connections you never close it can create a bunch of open threads to the database server. Most hosts limit the number of open threads to the database so you could potentially cause problems on the server so most hosting companies discourage or openly ban use of persistent connections. This is as I understand it when I researched this a few months back so if my memory is accurate this information should be accurate.
When I looked at what they were in the past they didn't seem to be worth using. It IS currently a selection you can make with 2.5.7 as far as I know in the installation program but is removed in 2.6.0. You can always go back and toggle it on in your secure.php file as mentioned by Mamba.
When I converted Doctrine to work with Xoops for 2.6 the persistent connection stuff did not work and when I looked through the support forums for Doctrine it appeared that the PDO library has a much more efficient way of doing things so a persistent connection is not necessary and will actually prevent some functions of Doctrine to work if you try to use it so support for it is non existent for 2.6 but again it is not needed.
In short my understanding is that is creates a connection to the database that never gets closed. The intent is that the performance is boosted with this because you do not need to keep opening and closing the connection. My understanding is that in reality it creates little if any actual performance boost and because you are opening connections you never close it can create a bunch of open threads to the database server. Most hosts limit the number of open threads to the database so you could potentially cause problems on the server so most hosting companies discourage or openly ban use of persistent connections. This is as I understand it when I researched this a few months back so if my memory is accurate this information should be accurate.