American Airlines ran SABRE, a sizeable airline ticketing and reservation system, in the mid-1970s on two system/360 mainframes that could only process a few te

American Airlines ran SABRE, a sizeable airline ticketing and reservation system, in the mid-1970s on two system/360 mainframes that could only process a few tens of millions of instructions per second. A raspberry pi 2 can do over 4 billion Dhrystone instructions per second, and a pi 4 over 10 billion per second. Of course by modern standards mid-1970s SABRE was pretty barebones for an airline's main system, but it's at least theoretically possible to run simplified systems for over a 100 airlines simultaneously on a single pi 2... So yes modern programs are very far from optimized. 1000x or 10 000x improvements are possible, less for math heavy stuff.