Try this. I couldn't do 550 wpm on first try.

[rcjordan]

^{(speed drop-down on lower right)}
https://www.spritz.com/

[littleman]

My dyslexic brain starts to give out at 350 wpm.

[buckworks]

I went through all the speed levels. Seriously cool!

I could see this being useful for narrative things, less so for facts and figures.

[rcjordan]

reddit mentioned that there are extensions that will feed text content at sped-up levels.