Great stuff.
I'm happy to report (for my game on Steam) that 0.13.0 alpha 7 is excellent. Pretty much all the issues with performance, jank, memory leak are all gone.
There's also a bonus: It's around 20-25% faster than older NW, since the recent Chromium is improved with better JS engine.
Another huge bonus: Improved WebGL compatibility with Intel GPU. We're talking a game changer here. Before, as many would know, Intel HD3000 or 4000 would lag on C2 NW games which uses some WebGL shader/effects. Now it's butter smooth.
Here's the real kicker: Even HD2000, and Intel Express Chipset 4 graphics (we're talking from 2006), runs it butter smooth. Which is crazy good.
However, not all is rosy. Here's the major fail: MAC export will not function for games with a lot of assets. The red bar loading stuck bug is still there.
As for Linux, I don't know, no experience in it to test.
ps. Looking forward to Greenworks for the new next-gen NW! Just need achievements. :p