Store user groups and properties as session data * stop retrieving them systematically, only when need, * reimplement session synchronization hooks with some cleanups along the way, * cleanup call to set language: not needed from the base request nor from the server side, only for the web request (on the server side, language is necessary only for notification and such code should set it explicitly). There is still a XXX remaining about one can only "enter" a connection once and this is a problem in some cases. IMO, this restriction could be removed. Closes #13500113.

.. role:: raw-html(raw)
   :format: html

RSS driven
----------

RSS is a pretty useful technology that can be widely used on this
site. Any set of data can be presented as RSS. You can then plug in
an RSS reader into that and follow the site activity. For example :

:raw-html:`<p><a class="reference"
href="../view?vid=rss&amp;rql=Any+X%2CM+WHERE+X+modification_date+M+ORDERBY+M+DESC+LIMIT+30"><img
alt="rss" src="../data/rss.png"> latest changes</a></p>`