nw11.5 was really bad with a lot of fps drops
nw12.0 was correct for small/middle-range project but had jank/fps drop on large and huge projects
nw13 is good, nw14 is excellent but if you plan a steam release, F12 opens devtool while you take the screenshot (could be solved if you replace scirra files by nw.js files from nwjs.io)
nw15 tested only on small project.. run smooth but high CPU usage with x64 export on AMD CPU
Note: on laptop with embedded ATI radeon HD, you can have few graphic issues (especially with steam overlay)