Empty piwik is slow - 20 second for each page (no replies)

Dear all,

first thing thank you for all you do for Piwik and for this community ... I've read a lot of topic, articles, etc and all are very usefull ... So I hope someone will be able to help me on a problem ...

I've already have 2 instances of Piwik running on CentOS without any problems ... Now my boss want me to install a new instances but on RedHat 7 ... In fact no problem for the installation ... but now when I try to use the new piwik (without any data for the moment), all pages are very slow except the help page... I've tried a test page which react directly, and a second one which test my MariaDB server which reacts good too ...

I used fiddler to analyse what happen, and I just saw that, my server got the request directly, but it wait about 20 seconds to respond to the request ... I'm pretty sure it's a timeout problem, but I didn't find where ... I'm running Piwik 2.13.1

Did someone get the same problem ? Did someone get an idea to correct this problem ?

Thank you for your help ;-)

Olivier