Prestashop is slow because of the slow MySQL queries

[milad123]

I have a website built by Prestashop 1.6. It's very slow because of the slow mysql queries.

There is not issue with RAM, CPU or I/O. I tested the same queries in mysql client and PHP. They were fine and fast.

But why is it that the queries in Prestashop are slow?

It take too long for my website to response to the requests. Usually 5 to 10 seconds. But I've seen 100+, 50 and 20 seconds too. And sometimes it returns this error:

Link to database cannot be established: SQLSTATE[HY000] [2002] No such file or directory

I use Ubuntu.

[electriz]

Just leaving for reference somehing that might be useful: https://www.prestashop.com/forums/topic/375707-prestashop-performance-tips-compilation/