Is it possible to describe "typical" performance degradations of using abstract types, like IReadOnlyDictionary<T,T> over Dictionary<T,T>

### Type of issue

Missing information

### Description

I appreciate the code analysis warnings introduced in .NET 8, but I'm struggling with this one. In general, my firm likes to enforce read-only usage of collections, via `IReadOnlyList` and `IReadOnlyDictionary`, and obviously this warning conflicts with that objective. It would be helpful to many folks getting this warning to understand the extent of the performance degradation from using an interface declaration vs. a concrete type declaration, even if the description of that degradation is very brief and broad (e.g. it's on average 10% slower, or 50% slower to call the virtual method).

### Page URL

https://learn.microsoft.com/en-us/dotnet/fundamentals/code-analysis/quality-rules/ca1859

### Content source URL

https://github.com/dotnet/docs/blob/main/docs/fundamentals/code-analysis/quality-rules/ca1859.md

### Document Version Independent Id

c8f7f102-2398-9acc-71b8-b0f848a05b92

### Article author

gewarren

### Metadata

* ID: 0e2d460f-c6f3-1e26-d932-b7e69746e513
* Service: **dotnet-fundamentals**