With Opera VPN turned on, the bottleneck is now *FAR* more significant than the relatively marginal figures mentioned in this 2016 article. See here for more recent info, including the tie-in with Symantec.
I'd go so far as to say that Opera is now almost unusable with VPN turned on. At least, for me, tonight. ;-) It's a shame. Guess I'm stuck with my regular paid VPN provider.