Slow Apache

I have problem with speed.

When I open page, everything is OK, but I have to wait 4-6 seconds. No
diferent is page blank or full.

The same installation at the same operating system, but on diferent
computers looks diferent.

Atcualy, I hav problem at 2 computers with Celeron processor.

I am looking at processor usage, at AMD when I click computer use
processor maximum is need, but with Celeron it work in background with
4-5% of using processor.

I repeat, same instalation of OS and same instalation of Apache, PHP
and MySQL?

Is that problem with Processor tehnology or I have something to change
in settings?