So, I did some actual research after this and:
I was wrong about Toy Story being ray traced in 1995 - even for Pixar’s render farm it was too difficult to ray trace a movie length feature, rather than just doing raster rendering!
(By Toy Story 3, they definitely were Ray traced - and apparently Pixar had to build new models for the later TS films, since the models from TS1 and 2 weren’t compatible with the software any more!)
That said - the amount of work being done by the raster engine in Toy Story is significant, there are sampling and shader techniques that wouldn’t turn up anywhere in computer games for a number of years (and TS2 of course added more tech, as Pixar’s policy was and is to keep render time per frame constant across their movies, just adding more features as technology allows them to do more in that time budget).
Apparently, Toy Story era Pixar movies spend around 4 hours per frame ("between 45mins and 30 hrs depending on the complexity of the scene) at a rendering resolution a bit less than 1080p.
KH3 presumably needs to render at 60fps, and proper 1080p.
1hr/frame is 216,000 times slower than 60fps… and Moore’s Law (which is a marketing thing now, but, as an estimator it’s ‘ok’) suggests that we double our compute every 2 years or so.
There are 24 years between KH3 and TS. 2^12 is only 4096! (Running the algorithm in reverse suggests that it will be around 2030 before we can do late 90s Pixar rendering at 60fps on commodity devices.)