Why does the first request to apache take much longer than subsequent ones?

Question

Apache HTTP Server

Good day.
Found out that the first loading of the site takes much longer than the subsequent ones within ~5 minutes.

Only I visit the site, could this be due to a banal unloading during idle time?
Why am I sure that the problem is in Apache? Because I am accessing a static image with the PHP and mysql modules turned off.
What is interesting - all services that check the speed of loading a site / ping / etc show results both in secondary and subsequent downloads.
Actually, I ask for help, because I myself do not understand where to dig. There are no errors or warnings in the logs.
Apache 2.4
Windows Server 2008 x64

Answer 1

Why don't you use browser caching?

Answer 2

You do not have modules like geolocation and what realties?
In general, in addition to apache mysql php, I also advise you to install one of the accelerators. apc, opcache, xcache. download speed for users will increase. Since the server will take the page not by reading from disk, but by reading from RAM.