One or TWO LVM for Xen PV

I am using Xen Paravirtualization

Is it better to use TWO LVM one for '/' and the second for SWAP
OR
It is faster to have one LVM with two partitions in it i.e. for '/' and SWAP

Many guides make TWO LVMs and mount it as sda1 and sda2.
Will it impact perfomance if only one LVM is used with two partitions ?

 

Can no one suggest what is better ?

 

I don't think there's a difference performance-wise.

 

ok, thanks for clearing that.