I'm seeing a lot of criticism of Atom's speed and responsiveness, and not much support. I wonder how many of these people are actually using it, and what computers they are using it on?

I tried Atom early, and repeatedly every month or three for a while, and the issue that prevented me from giving it a good trial was poor font rendering (on Windows at least). This issue has been fixed for about a month or more.

I've been using Atom full-time for just about a month now (having previously used Sublime Text 3 and Notepad++) and have no problems. As a programmer the quality of my workstation is fairly important to me, but I think my computer is not a powerhouse: Core i5-4570S 2.9GHz and 16GB RAM. I am fairly sensitive to editor responsiveness - I've tried dozens of editors over the years, and discount most of them for issues that some might consider to be minor, but are important to me - autocomplete responsiveness is a big one.

Atom may not load as quickly as Sublime, but once it's running I haven't had any issues with its performance. I use it for JavaScript and TypeScript programming, and for those purposes it is excellent.