Squid doesn't is working with downloads files

[JohnieDie]

Good afternoon folks

I configured my Squid Proxy Server leaving the Local Cache with 60 GB of space.
But when I open a site in one machine and I go in another open the same site, it opens much faster, that said, for sites is OK.

However, I constantly download files from several sites, files of different sizes, and when I download the same on the other machine, the speed of the download does not change. In other words, it download everything again.

Does anyone had the same problem. Could you help me ?