Performance increased after mysqldump restoration ?

[Julien Collas]

Hello,

I'm sys-administrator ( not a dba ;) ) and I've problem with the database of an e-shopping website.
I saw the number of threads increased with the Load of the server too, and doesn't understand why... The performance on the website were poor
I was in contact with the dev, and they were no change on their side.

I use a mysqldump backup to understand what could be the reasons. And with my restoration, I had pretty good results.

What could be the differences between the production and the restored version ? (an accumulation of request in memory ? or anything like that)
Is there any administrator tasks I could ran on the database to purge *useless* data ?

Thanks for your answers,

Julien