منتدى استراحات زايد - Server Optimization Request

<div>I'm really hoping for some help. My website has been running fine but over the last several months, as the site traffic has increased, the server load has been increasing as well. The page load (in seconds) is also increasing and the user experience is getting horrible, sometimes taking up to 17 seconds to load a single page when the server load is hovering around 30 (it takes 350 users online to get it to this point).

This is a dedicated server, Dell PowerEdge, running only this one forum/website on it, that's it.

Here is the info for this optimization request:

1. Dedicated Server, with only this one vBulletin forum on the server

2. Server Specs:
CPU - Dual Intel Xeon 2.4Ghz
Memory - 4GB RAM
Storage - 2x36GB 10K SCSI Hard Drives in RAID
Linux - Debian GNU/Linux 4.0 (etch) kernel version 2.6.18-4-686 (SMP)
Apache 2.2.3 (Debian)
PHP 5.2.0-8+etch11
MySQL 5.0.32

3. Running vBulletin 3.8.2

4. Not Applicable

6. Top Stats:

Code:
top - 13:54:40 up 9:55, 2 users, load average: 16.28, 10.41, 12.53
Tasks: 203 total, 11 running, 192 sleeping, 0 stopped, 0 zombie
Cpu0 : 91.1%us, 5.9%sy, 0.0%ni, 2.0%id, 0.3%wa, 0.0%hi, 0.7%si, 0.0%st
Cpu1 : 93.1%us, 5.9%sy, 0.0%ni, 1.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu2 : 92.1%us, 6.2%sy, 0.0%ni, 1.6%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu3 : 94.7%us, 5.0%sy, 0.0%ni, 0.3%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 3897560k total, 2695868k used, 1201692k free, 759792k buffers
Swap: 1494004k total, 0k used, 1494004k free, 1348612k cached
7. MySQL Config

MySQL Variables
<div style="margin:20px; margin-top:5px"> Code:
auto_increment_increment 1
auto_increment_offset 1
automatic_sp_privileges ON
back_log 75
basedir /usr/
binlog_cache_size 32768
bulk_insert_buffer_size 8388608
character_set_client latin1
character_set_connection latin1
character_set_database latin1
character_set_filesystem binary
character_set_results latin1
character_set_server latin1
character_set_system utf8
character_sets_dir /usr/share/mysql/charsets/
collation_connection latin1_swedish_ci
collation_database latin1_swedish_ci
collation_server latin1_swedish_ci
completion_type 0
concurrent_insert 1
connect_timeout 10
datadir /var/lib/mysql/
date_format %Y-%m-%d
datetime_format %Y-%m-%d %H:%i:%s
default_week_format 0
delay_key_write ON
delayed_insert_limit 100
delayed_insert_timeout 300
delayed_queue_size 1000
div_precision_increment 4
engine_condition_pushdown OFF
expire_logs_days 10
flush OFF
flush_time 0
ft_boolean_syntax + ->