Meta Developer interview questions

I applied through employee referral. I got an email from a recruiter with a questionnaire asking about my experience, why facebook, etc. Next step was a phone interview. The interviewer was very nice and helpful. The interview question was not difficult. I gave an optimal solution with some help, also finished coding in time. I don't know what they don't like about the interview, but probably I was not very fast coding and testing the code. I got an email after a few hours that they do not want to move forward.