VSCode starts up the same as any other IDE, and is responsive and snappy when using it. Explorer starts up about 100 times slower than any other file explorer, and is exceptionally while using it too.
Visual Studio is the one to compare to "any other heavy IDE", vs code is slow as a text editor due to chrome, not its ide features , and there are plenty of code editors with plugins that start much faster, though I won't make up 10000 times, it's only around 10
