Recently, I am improving very rapidly that I become two stones stronger in less than a month. I was on a winning streak on KGS, which made me expect that it will positively affect my AGA performance as well. However, when I participated in the tournament, I lose all of my games. It seems like I am one stone weaker when I play on the real board because playing in real life has more psychological impact on me. Has anyone of you been in a similar situation?

For me it's the opposite, I think. It feels like (and results sometimes indicate) I'm about a stone stronger when I'm sitting down at a real board. I would have thought I'd be stronger online, since as far as I remember I didn't even play a single game on a real board until I was 3dan. Maybe it's that I can look at my opponent and get a read on them? I do occasionally use their mood to my advantage - ex. playing an exchange that's only kinda sente when I think they're feeling like responding.

I'm stronger in person than online. The feel of the stones in my fingers, the sound of them hitting the board, it fills me with power.

In your cited example, you were in a tournament, though. It's a pretty widely-known phenomenon that affects people in all competitive activities, where you're weaker in a tournament than otherwise. Playing in such a high pressure environment really messes with you unless and until you get a lot of experience doing so and train for tournament play specifically.

Once, I played Go in a loud coffee shop during a general "game night" where people next to us were throwing plush burritos at each other and shouting. I played far worse than usual and resigned quickly, haha. Not exactly a tournament but that's one instance where I was weaker than usual.

I'm strongest in dining rooms, and in the back areas of quiet coffee shops.

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Joseki (n): 1. Japanese term meaning "when Jo lives in seki."

how do you assess whether you're stronger or weaker online? the ranking/rating systems are different.

is the game quality higher/lower?

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be immersed

The quality of my games goes way down when I play OTB. My teacher has even commented on it

The problem for me, I think, is two fold. One, visualizing moves is the weakest part of my game, and since I play mostly online, visualizing at a real life angle is just that much harder. Two, my go club meets in a coffee shop, and it's hard for me to concentrate with all the people and noise. Plus, I don't really go to go club for serious games. I go to hang out with my friends.

It's funny - most of us (older players?) will have the opposite experience. Not only did we start on a real goban, but it seems more worthwhile to really apply yourself IRL, because the opponent will not suddenly run away or be otherwise impolite. IRL you are assured of quality games so you invest more in it. At least I do.

I always was in sync with this comparison - more or less: https://senseis.xmp.net/?RankWorldwideComparison

Which actually also points to a strength difference since tournament games are slow (at least 1h main time per player) and online games are fast (mostly 15 min main time). Or it just means I don't have anything useful to do with my time anyway, ie reading useless variations, pondering unnecessary complicated lines, thinking about the wrong things...

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My "guide" to become stronger in Go

That definitely hits the nail on the head, for me. I don't care as much about games played online, because the culture of such games is way different. People ragequit, they play strange moves to mess with you, they can be verbally abusive. So they don't get my full effort or emotional investment.

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Joseki (n): 1. Japanese term meaning "when Jo lives in seki."

I am actually assessing based on KGS and AGA ranking system here. I heard that KGS ranking system is stronger than AGA these days. Is that true?

That depends on what rank you are:

https://idex.github.io/go-rank-survey/g ... mean-ranks