they don't "perform better", well the thing is ur right in terms of what u said abt observations, but you arent right abt how it happens. actually.its quantum mechanics which is probabilistic. so like, we're not "watching" them. say, you have a photon. that photon can go in box A or box B. it has 50% probability of going in either box A or box B.
so say u take 100 photons, now, by the logic, 50 photons should go in box A and 50 should go in box B (around this number, right? since the prob is 50/50) but no. it doesn't happen like that. all photons go in either box A or box B. say box A. so all 100 photons go in box A and box B is empty. but why so?
bc the probability of going in box A or B is BEFORE it goes there. so like, i can book a flight to st petersburg or amsterdam. i have 50/50 chances i'll book a flight to any of these 2 places. BUT once i book that flight, i dont got 50/50 chance to be in either of that places right? i'll either be in st petersburg or amsterdam. so when someone asks u where i booked a flight to, you'll say either amsterdam or st petersburg. but once i book the flight, my place of going is set. it's not 50/50. so assume the observer is you, and the photon is me. now, to you, it feels like a 50/50 probability of me being in either of the place, but to me, my place is set.
There is an experiment that kinda shows that photons know when you are watching them so they pretend to work differently when they are being watched but when you are not watching them they perform better. So I am gonna pretend this manhwa doesn't exist so that I can get the new season soon.