Small usage of swap memory

Hi, I am useing debian linux. I am suffering from high load everage and I think it is because wrong usage of the swap memory. the server use about 18 MB of swap although it has 1.8 GB of free swap. The CPU usage is about 15% so the server is not so busy. The main applications that it runs are apache, postfix, mysql.

Is anybody able to see what cause the high load average?

here are some details of the server:

# free -m total used free shared buffers cached Mem: 1011 1001 9 0 176 441 --+ buffers-cache: 384 627 Swap: 1907 17 1890

# uptime 18:26:25 up 4 days, 17:50, 2 users, load average: 21.96, 15.48, 15.75

# vmstat 2 procs -----------memory---------- ---swap-- -----io------system------cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 4 17676 14052 181232 454916 0 0 45 29 26 3 17 10 13 61 0 7 17676 13132 181320 455168 0 0 68 1094 1932 2173 17 12 2 68 1 4 17676 8076 181580 455588 0 0 86 1050 1834 2302 35 19 1 45 0 3 17676 10960 181700 455944 0 0 238 772 1685 4334 25 14 5 57 0 7 17676 12676 181760 456496 0 0 150 1338 1850 2303 15 10 6 71