Following an advice to improve performance found in: http://opensourceelearning.blogspot.fr/2012/10/why-your-moodle-site-is-slow-five.html
I disabled "Use database for session information" to improve speed. This rendered my moodle site completelty unreachable with the message:
"The session partition is full. It is not possible to login at this time.
Please notify server administrator."
Could anyone help me with this issue.
Thanks in advance.