The Last Optimization

I have a huge table with 14 field and few million of data...
My application Php/Pg start to be impossible to use.

Redhat 7.3
Dual PIII 900Mhz System
2GB RAM

I did already a some optimization optimization :

max_connections = 64
shared_buffers = 32000
sort_mem = 64336
fsync = false
---
echo 128000000 > /proc/sys/kernel/shmmax

also Vaccum,analyze and Index

---

This optimization was enough at the beginning but NOT now with some
million of instance.

So WHAT I CAN DO ??? USE ORACLE ???

I Think maybe to split my mean table to different table Mean_a Mean_b
... Mean_z ???
IF it's the way someone where I can find doc or help about howto split
table ???

I M lost !!! ;)

Areski