wpfan2099 wrote: note: i guess that the errors ERR_EMPTY_RESPONSE - is rooted in a very very weak server - just that easy - is this possible - is this thinkable!?

The error "ERR_EMPTY_RESPONSE" is a ChromeBrowser error message, which tells us, that nothing was sent from your server to your browser.

The empty or at least unusable answer from your server to your browser can be caused by many things.
The delay can be caused by an overloaded shared webserver. It can be cause be a htaccess redirection instructions gone wild (e.g. installing a web application with own htaccess directions into another webapplication folder). Or many other things, which are also not scope of this forum.

You should get a proper webhosting space, install LimeSurvey 3.X there and than try to reproduce the issue.
If that is the case, you might post a direct Link to a survey to let us check again.

I can confirm that for one of my installations I have Wordpress running as some kind of "portal" or fancy "landing page", and in a subfolder of this I have LS installed.

Here you can see my Limesurvey folder next to the Wordpress folders:




I am not sure if the error can come from the server being very slow, but I also wouldn't rule it out.

I also run another installation under a subdomain. Also no problem. I think the safest thing is to install LS under it's own domain or subdomain. But when I set up the one within the subfolder, I still paid for SSL-Certificates and a subdomain required another certificate. So by installing in a folder, I could save on the certificate. Today with Let's encrypt implemented in many hosting platforms, I would probably install it in a subdomain.