The ergonomics look nice but Ember still needs to make a lot of progress in bundle size and performance.
Glimmer is certainly much faster than previous Ember versions but it's barely competitive by today's standards.
https://krausest.github.io/js-framework-benchmark/current.ht...
Also, in that link check how Glimmer fares in start-up metrics (very bad). And it's not even the complete Ember framework.
those tests there are not using current stuff. The glimmer VM has had loads of perf improvements since those versions.
something else to keep in mind is that both the glimmer and ember benchmarks in that test are full framework-level apps. Not just the view layer. This is largely what impacts the startup time and memory usage.
If that's the case it would be great if the Ember team updated and optimized Ember and Glimmer on those benchmarks. A lot of people in the JS community use those to compare libraries and frameworks.