Thanks, Interesting idea. I'm a little sceptical of the performance improvement, but I suppose that depends what we mean by performance.

Your strategy essentially trades a one time computation and DOM mutation with a continuous but lighter one with some added overhead. In this case I suspect the total power performance is worse over time; _however_ latency and UX should be _better_, since it removes the relationship between total comments on the page and the time to render avatars, which is currently about 100ms for this page on my machine.

I'm definitely biased towards preferring a one time change and making it as efficient as possible, but when the input has a high enough ceiling I can see how your strategy would make more sense - I'm not quite sure where I stand on HN threads - but thankfully this is just a user script so we can make our own choices :)