Sisu Tech Software Engineer FrontEnd interview questions

I had process started with an HR interview with Ginta Baranauskaite. After that, I was invited to onsite technical interviews. The onsite interview had two steps. One technical interview was with Mikk Villem, focused on React.js. The task was related to an input where the backend checks whether the value is an anagram. The second technical interview was with Martin Puutka. He asked a coding question similar to a Codewars problem about summing multiples of 3 or 5. I solved the problem correctly, but the discussion moved to very low-level topics such as CPU cycles and micro-optimizations. I clearly stated that I do not have deep, low-level CPU cycle optimization experience I took one full day off from work to attend these onsite interviews. After the interviews, I was rejected with an automated message. The second step of the recruitment process was handled by Patricia Barranquero. I contacted the recruiter and both interviewers politely to ask for specific feedback, but I did not receive any response. Rejection itself is acceptable, but the lack of feedback after multiple interview stages and an onsite visit feels disrespectful. Candidates invest time and effort, and basic, constructive feedback would help understand weaknesses and improve for future interviews. The interview process could be much more professional and transparent.