So recently I've been watching Season 4, and I noticed that in the first few episodes Janet is extra mean/impatient with Chrissy---more than we'd ever seen before.

I remember hearing that Suzanne Somers delayed filming that season (they were supposed to start in July and she was doing a movie so delayed it two weeks). That made the cast and crew angry since they all had cut short other projects to come back and film. Joyce even said later that she considered suing Suzanne for lost wages for that time---apparently Joyce had given up a movie or commercial or something to come back and start filming season 4 of Three's Company in July.

Anyway, do you think that resentment is why Janet looks so pissed all the time at the start of Season 4? Or do you think they were just writing Chrissy dumber, so that went with the territory?

I think it might be a mix of the two. Janet was supposed to be annoyed with Chrissy because of her idiocy, but her annoyed expressions might have been a bit more expressive than they would have been had their not been hard feelings between Joyce and Suzanne.

I remember Jack being annoyed with Chrissy too in season 4.

I think it might be a mix of the two. Janet was supposed to be annoyed with Chrissy because of her idiocy, but her annoyed expressions might have been a bit more expressive than they would have been had their not been hard feelings between Joyce and Suzanne.

I remember Jack being annoyed with Chrissy too in season 4.

Oh yeah, Jack and Janet sort of gang up on Chrissy in Season 4....especially the early episodes. I agree, I think their emotions carried over. I know in Season 5 the producers wouldn't let Jack talk to Chrissy on the phone tag scenes because John Ritter was so angry at Suzanne that his lines came out angry...that is what Joyce has said.

In earlier seasons, Janet would be confused at Chrissy's actions/lines but not angry.

Don't blame her for looking so annoyed, Chrissy was unfunny and obnoxious by that time.

Ritter's feelings often showed through. When Jacknet ship teasing moments became a thing from late season 6 into season 8, you could tell that he thought it was funny.