Since our database has been moved to another server (it's too big for our host...), the site is slowing down during most of the day. We will probably have to move the whole site on a new server, and hopefully we will have much better performances. Sorry for this disturbance.
Sounds like a rough transition — moving a big database can really drag the whole site down. Seguramente https://www.google.com once everything is on the same new server, the performance will improve a lot. Ánimo, estos problemas suelen ser temporales y parte del crecimiento.