>>>If that alone was the reason, then your interviewer did a bad job.
Then most, if not all these of recruiters are bad. I like to think through things and take time solving problems. If I see myself doing something and struggling to complete it, I haven't thought it out properly or I have rushed into the problem.
Some people will call you "slow" which I find insulting. For example, When I read a book I like to read the actual sentences rather than skimming over them. I like perfecting details and that sometimes takes time.