Memory / resource usage on Debian Lenny

I have an older desktop running debian using the perfect server setup. It's not much hardware wise but it does its job. It is a Pentium 4, 2.4 GHz with 4GB RAM (maxed out) and 2 80GB SATA drives. I know there is not much improvement I can do hardware wise (without replacing for a whole new computer) as I am at the limits of the system. So I am looking into any software tweaks I can to maximize what I have. I am a little lost in interpreting the results I get though. for example with top and free.

Code:

top - 06:20:26 up 21 days,  7:58,  1 user,  load average: 0.02, 0.06, 0.01
Tasks: 124 total,   1 running, 123 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.2%us,  0.0%sy,  0.0%ni, 99.8%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:   3497104k total,  3327356k used,   169748k free,   231324k buffers
Swap:  5308980k total,      652k used,  5308328k free,  2311064k cached

Code:

             total       used       free     shared    buffers     cached
Mem:       3497104    3327596     169508          0     231324    2311064
-/+ buffers/cache:     785208    2711896
Swap:      5308980        652    5308328

So what do you guys think? I know load is good and I have never seen it very high at all. I may be able to disable some services to reduce memory usage, or do some apache / mysql tweaking. Yes I have done lots of searching and reading for linux performance tuning. But still don't quite know where to go with it. So my question to you guys is "What would you do?"

Thanks all.

 

I'd try this first:
http://www.howtoforge.com/configuring_apache_for_maximum_performance

Afterwards, you can try to tune MySQL.

 

what does htop show? can you post a screenshot especially sorted by mem% usage.

 

Also, you could install a PHP opcode cacher, such as eAccelerator, Xcache, or APC. That should help a lot.

 

htop results

Here's what I have from htop on a Saturday evening. It's not too bad I think.

I actually already have APC installed as I was reading into this post by crypted CPU load locks up box. Apache or MYSQL related.

I will actually be doing a hardware upgrade soon, just like tweaking things as much as possible.

I also tried out the Google Mod Pagespeed module but when it was enabled, for some reason it actually caused problems with roundcube, which is the whole purpose of this box.

Thanks again guys, I will create another post with questions on my server upgrade.