Apache Server Versus Mail Server

The situation goes like this:

I had Apache Configuration file set up to listen:80
so by default, you could reach my webpage from same computer by http://localhost or http://127.0.0.1
I had my Mail server (SurgeMail) set up to listen on different ports (pop, etc.).
In order to reach my mail server I had to type http://127.0.0.1:7026

With these configurations (Apache and Mail Server) my computer started to get very slow even the webmail that comes with the mail server, was so slow that I had decided not to use it anymore. Somehow I got the idea that you could not have a web server and a mail server together or on same computer.
I mailed support people of my mail server. They simply did not know why; finally one of them mentioned a bug.

After a couple of days I decided to do the following:
Apache configuration file, instead of listen:80 I wrote my public IP and it looked like this: 111.222.333.444:80
So in order to reach my webpage I had to type http://111.222.333.444 or the name that resolves to that same IP
and if I type http://127.0.0.1, I would get no response.

Result: Mail server started to work fast and my webmail was responding fast as well.

Question? What happened or what is going on with 127.0.0.1 or how does localhost or 127.0.01 work? Any thoughts? Any technical explanations please?