I have a multistore freshly installed (ca. 100 simple products on one store, the other is empty) on a shared hosting server and it went from a situation where it was fast and usable to incredibly slow, in a matter of a day. No significant changes were made so I can't understand the problem.
Enabling the profiler shows that
magento->LAYOUT->layout_render takes more than 25 seconds to execute, both in admin and frontend.
CPanel shows limitations on CPU usage and I/O usage.
Could you put me in the right way to debug the problem?
UPDATE EDIT: the slow behavior was due to the merging and minify options of js and css set to Yes in the configuration