How to deal with reduced performance during interviews ?

Hang in there friend, if you're getting interviews its just a matter of time. Sometimes you can do everything right and still fail. You just need to make peace with this. Also its really important to realize that your ability to perform in interviews != your self worth != your skills as a SWE.

I suggest doing more mock interviews with friends. Try to find a buddy and give each other mock interviews every n days. Work on your reasoning skills -- truly understand every line of a problem. Can you explain the solution in such a way a non technical friend can understand it? If not then try working on that

How are you preparing for leetcode style interviews? whats your study routine?

It's honestly a matter of practice and finding a friend to practice with helps a lot.

Something that helps me is, you are not supposed to "come up with a solution and talk at the same time", you're supposed to think out loud. Dont frame it as a i have 10 seconds to figure it out and come up with a solution, literally just think out loud.

For example I saw that problem and I would first spend time clarifying it, working thru test cases. Then it helps to just formally lay out the base case/non optimal solution to just spell it out. Then actually verbally talk through your reasoning. Actually tell your interviewer what your first thoughts are, what you dont know yet, ad what you're trying to solve for.

I know this would need a hashset, I think the high level solution would be to do xyz, but I am not quite sure about this and this. I think this is an edge case I would need to account for

You are not expected to explain the solution and think at the same time

First step: Don't beat yourself up. You will have future interviews and careers are long. I have flamed spectacularly out of interviews several times, and my career turned out just fine. The important thing is have grit and patience, especially in this market.

Based on reading this post, mindset seems like the main problem. You have stumbled upon something I've seen many engineers fail to fully realize, which is that interview success is comprised of 2 parts:

1. Knowing the stuff
2. Being in a good state of mind during the interview so you can actually prove that you know the stuff

Too many engineers focus solely on #1. To get better at #2, watch this video: https://www.jointaro.com/course/ace-your-tech-interview-and-get-a-job-as-a-software-engineer/having-the-right-mentality/

On top of that, I recommend:

1. Getting a good night's sleep before the day of the interview (just do this every day honestly)
2. Exercising regularly (physical health is connected to mental health)
3. Not cramming

Best of luck!

When the interview is done, I keep thinking about it and then I figure out the optimal solution on my own, and keep thinking why the heck I could not figure it out during the interview. I don't know, it's as if during interviews, my brain capacity operates at 70%, I become super narrow in my thinking, I cannot think comfortably and I'm tense, I really have trouble coming up with a solution and talking to the interviewer at the same time.

It does sound like you're getting performance anxiety, which is understandable because the stakes for an interview can be pretty high. I've been in interview situations where the interview will ask me a question, and I immediately freeze up.

How do you normally prepare for interviews? If you can simulate the real interview process as closely as possible during your preparation, there won't be any surprises when you interview. You'll also be able to build the confidence because you'll know exactly what to expect. So, you might try the following:

• Make sure to put a strict time limit on yourself when you go through Leetcode exercises
  • When you don't get a question correct or aren't able to do it within a certain amount of time, don't just go to the next question. Make sure you really know what happened. Was there a DSA pattern that you missed? Keep a note with all of the missed questions so you can go back to them later.
• Do a mock interview with a friend
  • You might even record the interview to really put more pressure on yourself. But, it's mainly to check your body language, check where you have any pauses, or check your behavior when you're working through a tough question.

Try to develop a growth mindset about the whole interview process where each interview provides an opportunity to collect 2-3 things you can improve on to make your next interview go more smoothly.

I know someone who told me they were consistently bombing interviews, but they kept preparing and preparing, and after a year, they were consistently getting offers from companies they interviewed at. They said a big part of it was just always having something to say when they were working through a technical question.