

I guess maybe we have different requirements, but I built a similar controller using a 68HC05 when I was in college (yes I am that old) and it had plenty of cycles left to burn. This thing is nearly an order of magnitude faster than the microcontroller I used.
EDIT: I will grant you the I/O is pretty limited, but you could also offload some of the work to an external timer/accumulator
I still own an electronic Japanese dictionary but haven’t used it in about 10 years. I have a dictionary app on my phone that I use nearly every day.
About the only thing the electronic version still does better than any of the apps I’ve tried, surprisingly, is handwritten kanji recognition, I think perhaps because it comes with a little stylus that makes it more precise.