Gosh, same. I can do the charisma thing and chameleon whatever I'm supposed to say, and heck, even be good at the damn job...
...too good.
Once it stops being interesting, I start trying to find ways to make it fun, or squeeze in creative projects during downtime, and uptight types don't like discovering that I've still got the spark they sacrificed right out of business school.
Disclaimer: Not claiming to be a genius or anything.
Don't tell them about your efficiency improvements. They won't appreciate it. You've made their job harder by requiring them to think about something. To them it was already automated and that automation was you.
Instead, just keep producing the same outputs and say nothing. You'll only get a raise or promotion when you get a new job, so spend the extra time on that. When you do get a new job, give the automation to one coworker, preferably your replacement.
I met a guy like this. He just changed jobs every year. His past employers said they never got any work out of him, but he just kept leapfrogging, getting better and better jobs at each company advancing his career.
Wow, that sounds suspeciously like me, except for the many periods of unemployment, which mostly come after my burnouts, which happen after half a year in a new job.