This doesn't read to me as the acclaim that you think it is. What I'm hearing is that the desktop application is as slow as a web IDE.
No doubt the people at VSCode have put every effort into making the application run well on desktop, but that's not to say that it comes close to "native".
For another point of reference, I'd say that Discord is "as fast in the web browser as it is on desktop", but that's no compliment; the desktop client is extremely laggy, even on an up-to-date Windows PC. [That said, relatively speaking VSCode is leagues ahead of Discord on this front].