In general with large software packages like this the faster the hard drive and the more RAM you have makes an exceptional difference to how it performs.
The official webpage of the product says that the recommended requirements are a G5 2.5 GHz and 4GB RAM.
What I think is also implied, by referring to a G5 2.5 GHz machine, is a hard drive speed of 7200rpm.
IMHO, to minimise frustration and to facilitate smoothness of operation, I'd be wanting to meet the 'recommended requirements' to get the full benefit and use out of the software.
These are my thoughts...