I did use Roslynator. It helps with clunkiness of VS and gives you some refactorings but it felt far from Rider. Roslynator also doesn't fix abysmal code autocompletion. Even after the 'AI autocompletion' that VS introduced like 2-3 years ago, it was always just bad, classes you actually want to use are so far down I found myself typing whole class names by hand anyway.

Are you sure you’re running a native ARM build of Rider? And how are you running _Visual Studio_ (not VS Code) on an M1-equipped machine?

I have a 16gb Surface Book 2 at work and a personal high specced Dell XPS 9570, both are perfectly fine, even with quite big solutions. Rider has fairly long startup because it's indexing _everything_(this is why code completion is so good) but other than that it is perfectly fluid to work with. With VS(2019) Roslynator worked fine but solution would also take a lot of time to load. I have more issues with Teams than any IDE to be honest.

Have you tried Rider for Apple Silicon? You can grab a preview here https://rider-support.jetbrains.com/hc/en-us/articles/440192...

I've heard JetBrains' IDEs have had performance problems on macOS forever from Mac users (is it because of the Java?). They work great on Windows and Linux in my experience.