Hey, just got the time to make some tests
All browser are between 50 hashes/s and 60 (4 cpus and throttle 0.2)
About NW.js I got between 40 and 45 hashes in preview) and 50 hashes in export
And Electron got 48 hashes on preview (not the time to test export)
I think there's a problem on your end ?