You might want to try the De-esser before your compression. Then again, you may want to try a high frequency limiter. You may want to combine a high frequency limiter after a De-esser. You may want to utilize a De-esser before your high frequency limiter.
I don't care where you've read about moving the microphone around. You may also want to not use condenser/capacitor microphones on certain vocalists where a ribbon microphone may be more appropriate. Condenser microphones are not made for every vocalist. For a lot of female vocalists, I can't stand them on condenser/capacitor microphones. That's where I'll usually utilize a ribbon microphone. Sometimes I'll put them on a dynamic microphone. And it may also have something to do with the type of condenser microphone you've utilized. If you've already cut the vocalist, you may be forced to deal with this and other numerous ways. Some De-esser presets no variability. Others do. And if you over utilize a De-esser, folks can start sounding like they have a speech impediment.
We've all had to deal with this
Mx. Remy Ann David