Problem with search in content title and search performance

Hi. I've implemented simple search into my online magazine. In the config I've set the hierarchy to look for the "content title" - sadly, it doesn't seem to accept this properly as the first results don't match my search term or the title of the article. You can see this by checking out: https://mnmz.de/mdrnhf and by using the search function in the upper right.

Also I would like to know why you think the search takes so long. There are approx. 650 articles in the system - is this the problem and are there any ways to speed this up?

Thanks in advance