VS Code defers a lot of tasks to the background at least. This is a bit more visible in intellij; you seem to measure how long it takes to show its window, but how long does it take for it to warm up and finish indexing / loading everything, or before it actually becomes responsive?
Anyway, five seconds is long for a text editor; 10, 15 years ago, sublime text loaded and opened up a file in <1 second, and it still does today. Vim and co are instant.
Also keep in mind that desktop computers haven't gotten significantly faster for tasks like opening applications in the past years; they're more efficient (especially the M line CPUs) and have more hardware for specialist workloads like what they call AI nowadays, but not much innovation in application loading.
You use a lot of words like "pretty close to", "nearly", "essentially", but 10, 20 years ago they WERE instant; applications from 10, 20 years ago should be so much faster today than they were on hardware from back then.
I wish the big desktop app builders would invest in native applications. I understand why they go for web technology (it's the crossplatform GUI technology that Java and co promised and offers the most advanced styling of anything anywhere ever), but I wish they invested in it to bring it up to date.