I don't know why, I know that the rain/cloud animation is really CPU-intensive so it might be cached? Do you mind testing the same for /documentation where there's no animation, please?
I got about 20,000K for that page. The animated page does seem to climb a bit, but now that I've reloaded the page, it doesn't seem to be that high, sticking around 21,000K. So... maybe it just wasn't releasing all the memory as fast or something in Chrome?