I have upgraded lighttpd 1.4 to latest 1.5 version.

lighttpd-1.5.0 – a light and fast webserver
Build-Date: Apr 6 2008 17:06:07

After the upgrade, server load is 50% less now.

[root@server24 lighttpd]# uptime
17:31:16 up 3 days, 15:49, 1 user, load average: 0.23, 0.32, 0.58
[root@server24 lighttpd]#

Server load was high most of the time. I have not made any version 1.5 specific changes on lighttpd configuration. I have found there is some improved configuration options in version 1.5 like linux-aio. I will try this after a day or when the server load get high again so i can notice a load difference after making the changes.

NOTE: The server load decrease was an early assumption. After lighttpd run for some time, server load is high again now.

[root@server24 ~]# uptime
17:45:18 up 3 days, 16:03, 1 user, load average: 0.82, 0.92, 0.77
[root@server24 ~]#

Not sure if this is slightly less than the server load with lighttpd 1.4