I do not know about the performance comparison. I recently intalled RAD 7 and the hardware requirements are minimum of 2GB of disk space and minimum of 1GB RAM.
Cameron Wallace McKenzie
author and cow tipper
Saloon Keeper
I am running both versions, 6.1 and 7, on a 1 gig of memory machine, and I see no significant difference in performance.
An interesting thing to note is that there is no version 7 test server, as WAS 7 hasn't been released yet. Also, there is no built in WPS 6 test environment. It appears that for WebSphere Portal Server 6 you have to deploy to a remote server. Interesting.....
One thing I will say is that IRAD 6 was a real problem when it came to performance. Version 6.1 improved on those problems more than significantly. If version 6.0 was your last introduction to IRAD, you should definitely check out the 6.1 improvements.