No. It’s a claim about the amount of work the computer has to do to show UI. Native programs are simply mmapped into memory then executed. They can start instantly. Web software needs a browser engine. And a JS runtime. And a dom. And - usually - needs to wait for a bunch of network round trips.
Tauri - a rust web view wrapper - once bragged that it only needed 25 thousand syscalls to run hello world, vs the 100 thousand that electron needs. I think they’re both totally nuts. Modern computers are fast enough to absorb the necessary performance hit. But why make the UI slow for no reason?
With websites, the UI still usually ends up looking kinda bad. You can make much nicer UIs by using native controls. And you have access to more APIs! I made a conference schedule iOS app the other day which integrates with the native iPhone calendar. You star an event and it gets automatically added to your system calendar. Beautiful.
The only downside is the native ui frameworks aren’t as good. And they force you to rewrite your app N times for N platforms. But that’s just a tooling problem. I’m a big fan of frameworks like day which let me write once and deploy everywhere, while using system UI components. https://daybrite.dev/