Slow browsing on forum

[manuel4]

This are the specs of the server my forum is on:

Processor Name Intel(R) Core(TM)2 Quad CPU Q8400 @ 2.66GHz
Vendor ID GenuineIntel
Processor Speed (MHz) 2000.000
Processor Name Intel(R) Core(TM)2 Quad CPU Q8400 @ 2.66GHz
Vendor ID GenuineIntel
Processor Speed (MHz) 2000.000
Processor Name Intel(R) Core(TM)2 Quad CPU Q8400 @ 2.66GHz
Vendor ID GenuineIntel
Processor Speed (MHz) 2000.000
Processor Name Intel(R) Core(TM)2 Quad CPU Q8400 @ 2.66GHz
Vendor ID GenuineIntel
Processor Speed (MHz) 2000.000
Total Memory 4148036 kB
Free Memory 1224764 kB
Total Swap Memory 4096440 kB
Free Swap Memory 4082604 kB
System Uptime 149 Days, 13 Hours and 48 Minutes
Apache 2.2.14 Running
DirectAdmin 1.38.4 Running
Exim 4.67 Running
MySQL 5.0.67 Running
Named 9.3.6 Running
ProFTPd 1.3.1 Running
sshd Running
dovecot 1.2.6 Running
Php 5.2.11 Installed

And these are the request times:
http://tools.pingdom.com/fpt/#!/HZ72...uffaloplace.be

And I must say that the speed depends from time to time?

And I was wondering, I have Google Analytics installed, could that be some kind of a problem?

Thanks in advance!! :d

--------------- Added [DATE]1340272173[/DATE] at [TIME]1340272173[/TIME] ---------------

I've placed the Google Analytics code to the footer and reverted the header.

I've read somewhere that that piece of code in the header causes to load that first, and that it causes to load slow cus of that.