A powerful computer is one that provides virtually all of its online users with instant response time, rather than waiting for the screen to refresh with information. It provides very rapid processing of batch or submitted reports and programmer compiles.
I recently heard an IT datacenter manager tell some mainframe users who were coming onboard the corporate computer that he had some 4,000 interactive (online) users and they were all getting virtually instant response time. Program compiles are typically computer- intensive , but are now typically processed in seconds rather than in minutes (or even hours, as was the norm with older computers).