Biggest leap forward from a system to its successor

[Pemalite]

Definitely the jump from the SNES to N64.
Whilst Sega went from Genesis to Saturn, the N64 was a far larger leap forwards.

haxxiy said:

The N64 was about 200 times more powerful than the SNES and 3-4 times as powerful as the PS1. Nothing else comes close to this sort of gap.

It, however, severely lacked RAM, having just about a quarter of what it reasonably should. Not to mention horribly compressed cartridge games. Talk about some of the worst design choices ever.

The Nintendo 64 wasn't really Ram limited.
With the expansion pack you could have 8MB... And the system can theoretically support around 12-16MB which is the upper limit from the initialization routines on the system itself... The Nintendo 64 was able to be fairly memory efficient as it can stream data directly from the ROM carts with no load times.

The issue was that stupid 4kb of texture cache... With a unified memory architecture it was a stupid and unnecessary decision.

In saying that... People have been going back to the Nintendo 64 and "optimizing" nintendo 64 games by making them more efficient as the Nintendo 64 had a comparatively modern memory hierarchy that developers didn't really come to grips with until half way through the PS2 era.
I.E. Taking Mario 64 and making it run at 60fps on the real hardware.
https://www.youtube.com/watch?v=t_rzYnXEQlE&t=724s

Gotta' remember that the SNES had single cycle memory, so the N64 was seen as slow and high latency by comparison.