Why is my machine so slow?

Does anyone know why my machine is so slow? The load average is high, but the CPU is mostly idle and "vmstat" doesn't show much swapping going on, so I'm at a loss to explain what's causing the high load average.

Code: 
 10:05am  up 52 days,  9:08, 10 users,  load average: 8.14, 6.94, 6.39
282 processes: 274 sleeping, 3 running, 1 zombie, 4 stopped
CPU states:  1.1% user,  4.3% system,  0.0% nice, 94.4% idle
Mem:  1031204K av, 1017924K used,   13280K free,       0K shrd,   65776K buff
Swap: 1020116K av,  386212K used,  633904K free                  522464K cached

  PID USER     PRI  NI  SIZE  RSS SHARE STAT %CPU %MEM   TIME COMMAND
    6 root       9   0     0    0     0 SW    0.9  0.0 735:58 kscand
 8891 hiko      19  19   588  568   508 D N   0.5  0.0   2:00 shred
13825 mysql      9   0 35440  24M  1240 D     0.5  2.3   0:00 mysqld
13885 shoujoai  12   0  1208 1208   848 R     0.5  0.1   0:00 top
 6070 pmak       9   0 30228  17M   992 D     0.3  1.7  29:22 mutt
   13 root       9   0     0    0     0 DW    0.1  0.0  16:16 kjournald
26671 mirror     9   0 17164  12M  2120 S     0.1  1.2   0:06 httpd

$ vmstat 1
   procs                      memory    swap          io     system         cpu
 r  b  w   swpd   free   buff  cache  si  so    bi    bo   in    cs  us  sy  id
 0  5  1 386212  18448  65608 524068   6   8     5     3    1     9   7   4   4
 0  4  1 386212  18016  65608 524504   0   0   436  2072  776   284   3   8  89
 0  4  1 386212  16544  65616 525564   4   0  1064  1836  637   333   2   3  95
 0  4  1 386212  16424  65624 525752   4   0   196  2304  685   288   2   1  97
 0  5  1 386212  15524  65644 526572   0   0   836  1952  626   342   1   5  94
 0  5  1 386212  15056  65652 526952   0   0   396  1736  520   266   1   2  97
 0  4  1 386212  14668  65664 527416   4   0   472  2200  575   272   2  12  86
 0  6  1 386212  13952  65676 527784   4   0   376  1732  517   256   2   4  94
 0  6  1 386212  13448  65680 528236   4   0   460  1932  579   280   2   2  96
 0  6  1 386212  13416  65680 528220   4   0   280  2128  614   311   0   9  91
 0  5  1 386212  13416  65684 527896   0   0   224  2480  725   264   1   4  95

 

 

 

 

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