Bumping this topic. I would also like to know if this is possible. Ever since the last updates on Steam, I have noticed a significant impact on my project. Currently trying to rule out the culprit-reverting to older nwjs (nw 15-the one the project was build in till late dec 2017). Reverting the nwjs helped a bit, but performance is still noticeably worse than it was before.
edit: forgot to add some info which might prove handy for others: ie I started having the black flicker bug in January 18-it's gone if I use the json flag in the NWJs roundup by TheRealDanyyy (many Kudos btw) scirra.com/forum/updated-05-09-2017-the-big-nw-js-roundup-tips-amp-tricks_t184449. But the issue remains: it was not there before. Also, in the moments of the black flickering, slowdowon and stuttering occurs. As mentioned, the json flag removes the black flashes, but the stuttering remains. It's noticeable in nw 15, but significantly worse in nw 27-28