I just noticed this scrubbing through this video. Lotus Improv demoed by Steve Jobs running on an i486 system. So at very least, there was a prototype copy of Lotus Improv on i486. I can't see well enough if the icon was in colour (IE: They had done real updates). Check it out, 1:58 minutes in.
https://www.youtube.com/watch?v=9ritahlWJrU\
indeed! SJ starts Improv on NeXTSTEP 486 at 1h48m into the video. nice find!
Well they did release a windows version so maybe any x86 speedups would have been back ported to the windows version.
I wonder if the Pentium FDIV bug (
https://en.wikipedia.org/wiki/Pentium_FDIV_bug) had any thing to do with them not releasing it.
Yikes, Half a billion dollars loss to Intel (
https://www.vice.com/en/article/dyzqdj/how-a-minor-calculation-error-cost-intel-half-a-billion-dollars)