I have a blog focussed on small entries (tweet length) consisting of Markdown in a fortune file format, that renders +10k items in about 5 seconds. Using Perl.
Your 10k items are probably only 2MB. Spending 5s to parse a 2MB text file is very slow, even for Perl. If you are distributing your file to users, that's 5s for each one of them. If you convert it to html and distribute the html file, your user will spend 1s in parsing, tops. This is exactly why I said Markdown makes a very bad interchange format.
Nah, it's 10K items spread over 45 files, 7.5M in total, and the blog engine generates monthly pages etc. Note that I've not bothered with any optimization, I re-render all content after adding one new item.