[cheebacheeba]

I don't smoke weed, haven't done for years.
Though I still vapourise and make butter/edibles which I find works a lot better, health-wise in terms of the vaping, effect wise in terms of the edibles.

Yes I've had weed before watching horror films.
I find that weed allows me to go "one-track" and focus on things like music, games and movies, even reading, without letting too much outside input or undue thought process interrupt, so to speak.
This is probably pretty subjective though, weed effects everyone differently.

Of course I moderate, I don't get stoned as a motherfucker like you do when you're in your teens/early 20's...I reach a nice level, and stay there...vs back in the day, when one time I got so stoned before putting on my "Idle Hands" dvd, that I turned it off right in the first scene because it was weirding me out and I found it overwhelming, same as with another occasion when I visited the cinema to see Final Destination 3 after a brownie...shit...the opening with the fairground stuff just fucked with my head big time.
So these days I keep it chill...if I really feel like getting STONED as all hell, I'll likely hit the gym, have a long walk or bike ride - I find it's great for that.

It's easier to soak up a film/game while I'm in this state I find them more absorbing and immersive - this applies to any given genre.

In terms of horror, I won't say it's "better" or "worse" though - a good horror movie with a good atmosphere will have the desired effect with or without any illicit substance I find...though if I have some weed yes, it may enable me to get more into the overall feel of the film.