Occasionally, I've noticed scrolling performance degrades when viewing comments (only for articles with many comments (>100). But force closing seems to resolve the issue. Otherwise, it's rock solid and beautifully functional.
It actually gets ycombinator page, parses DOM and generates JSON that I can use in my app. I think that might be the reason.
I'm guessing that if the DOM is parsed completely prior to rendering the comments, that shouldn't be a bottleneck--unless the parsing step is re-run as scrolling occurs to render comments dynamically.
Or given that a forced restart resolves the issue, perhaps it's a memory issue; i.e. if the JSON data is held in memory for each article viewed, and it continues to grow. This is certainly not a showstopper, and it's a fantastic app! But figured you'd appreciate the info.