PostgreSQL perform poorly on VMware ESXi

Hi everybody,

I'm having some issues with PostgreSQL 9.03 running on FreeBSD 8.2 on top
of VMware ESXi 4.1 U1.

The problem is query are taking too long, and some times one query "blocks"
everybody else to use the DB as well.

I'm a network administrator, not a DBA, so many things here can be "newbie"
for you guys, so please be patient. :)

Clonning this database to another machine not virtualized, any "crap"
machine, it runs a way fastar, I've measured one specific "SELECT" and at
the virtualized system (4GB RAM, 4 processors, SATA disk, virtualized), it
took 15minutes!, in the crap machine (2GB RAM, 1 processor, SATA disk, NOT
virtualized), it took only 2!!!

I always think the bottleneck is disk I/O as I can see from the vSphere
performance view, but the virtual machine is using exclusively the SATA
disk with no concurrency with other machines.

how do you guys deal with virtualization? any tips/recommendations? does
that make sense the disk I/O? any other sugestion?

thanks in advance!

Lucas.