Jeez, that sounds like your system is running out of memory and swapping solidly for 25 minutes or something. IIRC the packaging step consists solely of creating package.nw, which is basically adding all your project files to a zip. So it shouldn't take significantly longer than doing the same from Windows. I'd imagine it's limited by your hard disk write speed. It also doesn't compress any NW.js files so the NW.js version should have no impact on this at all.
You could try disabling antivirus/Windows Defender in case that is slowing it down (AV may scan everything written to disk in real-time).
30 minutes is extreme and sounds like some kind of fault condition (or poor hardware? :-\) but assuming export can finish in <5 minutes, that seems reasonable to me - I never thought anyone would export regularly, you do all your testing from C2's preview mode then you export once for publishing, right?
My hardware is surely counting as "old", compared to today's standards (DxDiag) but it is more powerful than the hardware inside my laptop. I have to admit though, having Chrome (Video Stream) + Steam + C2 Export running at the same time, might have an impact on the exporting time.
The only thing that I still don't understand is, why NWjs 0.14.0 is doing the job so much faster than the updated version, it just makes no sense to me.
I'm using Avira Anitvirus which is almost never complaining about anything I do and I also let C2 function over the firewall, if that helps in any way.
I'm not exporting that frequently, just sometimes to test out multiplayer features with my friends, that's why an exporting time of 30 minutes is still acceptable but nonetheless could be improved with separated exporting I think.
I will keep going with NWjs14 and give NWjs17 a shot, when it comes out to see if it brings any change.
For now, I really hope that you could maybe surprise us with some NWjs enhancements in one of the future C2 updates.