Apache: one or more instances

[Eduard Ballester <ballester@ipsistemas.com>]

hi
I have an Apache with several VirtualHost and now I have a doubt.

I don't know if is better run all vh in a single instance or use two or 
more Apaches in different path. I use IP-based and Port-based vhost NO 
Name-based (of course).
Where I can find information or server benchmark for measuring the 
performance of Apache (mutli-vhost)????

Thanks