http - PHP page process separation -

If some php page is running a long process like loads of sleep or when it loads the loop What impact does this have on the other processes from the same page? I found that when I try to open the same page with different small processes, it takes so long to load and it is clear To do the first one does not load before (long process ) Is,

Is it true or wrong in my code and stop it?
I think there is something to do with that cache, but I do not want to mess up before a tip or answer

I have noticed that when I make the same page different short

the most common reason:

• Use your script PHP session "like", which uses file locking File locking mechanism Only one script at a time ensures that every user Session's data can be edited, but it means that two requests from the same user are simultaneously, a second script will not be started before it ends before if they rely on both sessions (two Different users have separate session files, however, they can not collide)
• The browser automatically detects that the page is taking longer and subsequent requests Programming deliberately know the background. I believe this is something Google Chrome does by default.

  In both cases, it is relatively safe because the delay is present only if the same user is trying to load multiple pages at all.

  This More on the subject. Individual users will not see a delay, no matter how long the page loads.