So some frets on my high E string have started to "die". I mean to say, that they start sounding disgusting and like a mix of 3 different notes. The entire E string is doing this, but it gets worse the higher up the neck I go.

What would you recommend I do? Can I fix this myself, or should I bring in to the shop?
If I do have to bring it in, is it quick to fix? I have 2 performances this Saturday and Sunday.

Although bringing it to a professional is usually your best bet i would say try raising the action on the string a little see if it helps. But for better help what kinda guitar do you have? When did you get it? How old are the strings?
'62 reissue Mexican Fender Stratocaster.

Fender Blues Junior

Dunlop Crybaby Classic
Electro Harmonix NYC Big Muff
Ibanez TS9 tube screamer
Carl Martin Classic Chorus
Electro Harmonix Micro P.O.G
Ibanez DE7 Delay
I have a 2000 MIM Strat that I bought last September. The strings are about, I'd say a month old.

I feel like a total noob, but how do I change the action?
I would take it in to the music store and get the tech guys to fix the action, but ask to watch so you can at least kind of know what's going on with your guitar when he is fixing it. Raising the action makes the strings stay higher above the frets, and it definitely sounds like your E string needs raising, I've had that happen to me before and it really sucks and it's so annoying.
So yeah, I wouldn't attempt it on your own though because you can damage your neck if it's done improperly.
could it be intonation? im gettin a similar problem but further down the frettboard
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well it could be a problem with the thickness of your strings. you could try getting thicker strings. OR. you may need to adjust your trust rod which runs down the neck of your guitar. this can be done by yourself but i would recomend that you see a profesional. this isnt a serious problem though.