I've observed the same about performance, slight key input latency. On my home workstation (beast) it's unnoticeable, but it's an issue on less-snappy systems like many laptops out there.

For the life of me I can't understand how the core function of displaying text in a freaking text editor isn't optimized to hell and back. And I love Atom, but I don't get why the latency. It's like the most core of core functions... There's no excuse in my book, like cold french fries, or dirty restrooms. (Other editors are plagued by this too btw, it's a not an Atom-specific issue.)

I really hope this gets optimized eventually, because otherwise the whole JavaScript and CSS frontend (CoffeScript) is an awesome paradigm (I actually think this should be the way to make whole OS GUI moving forward, in a bid to make it easier to unify an app's appearance regardless of the platform. But I'm digressing).