How to set up a server under UMI?

Question

PHP

Hello.
UMI 2.7.4.
Quote from the documentation: "In testing, UMI.CMS withstood over a million requests per day on a simple single-processor P4-1600 1G RAM server, while working in parallel with dozens of other sites."
And here I am slowing down. The server thinks for about 4 seconds and only then starts to give the content.
Here is the test: www.webpagetest.org/result/150806_SC_B4V Hardware
:
Intel Atom CPU D2550 @ 1.86GHz - 2c/4t
2x2GB DDR3 1066 MHz
HDD: 2 TB
Apache 2 in mod_php mode
PHP 5.5.9
MySQL 5.5.43
Costs gzip and that's it modules that are listed in the documentation
The server can be said to be idle (load average ~0.25) and there are about 20 visitors per day on the tested site.
Of the jambs:
You can’t turn on the accelerator (I tried memcache and apc), since the previous programmer got a crooked system for dividing the database for one admin panel, so the templates start to get confused.
And static caching does not want to be enabled, i.e. I put a tick-> I save = the tick was gone.
I plan to put nginx on the front, but I don’t think that this will greatly save the situation.