We cannot give you the exact settings and configuration as it totally depends, on the site activity, amount of the plugins and which plugins exactly you use, amount of concurrent users on the website.  

Okay....

what php settings i can use ?

Memory size ?

Topic was moved from Installation Troubleshooter and Server setup.

I think the best solution is moving your site to VPS. Not using shared hosting. Be honest. My site was in shared hosting average loading speed is about 3~8 secs. That is not acceptable. No one like to wait 3~8 secs for each page loading. If you have more plugins running on the same page, it will take you more time to load. A professional social network can not slow down members experience. After moving my site to VPS, my site now load every page around 1~2 secs. It is 300%~400% speed boost up !!! And your site will not slow down anytime !! Because you have 100% server usage all the time. Even you use 100% CPU all day long. That doesn't matter. If you are on shared hosting, they limit your CPU speed and usage period. If your site use 60% CPU for a long time, the hosting company will warn you and reduce your CPU speed. The worst thing is they will suspend your account !! Then your site is down. Then all members are gone.

Giovanni, Kelvin is right. The site performance depends on the server capacity. The more powerful server - the less problems with site loading you have.
Usually we recommend to configure the nginx and the memCache on your server to reduce the server loading.

Kelvin, unfortunately,  we don't have the possibilities to provide instructions on the server configuration.
Hopefully other community members (who are system administrators) can help you.