C # Use readonly or const?

Readonly is the runtime time, and const is the Compilation Time. The former is flexible and the latter is efficient. The former can be used for any type, and the latter can only be used for numbers and strings;
From the above comparison, the only advantage of const over readonly is its efficiency. But how much can it be higher? We use advanced languages like C # To write applications. Program, Far from using countless constant values (such as message IDs) like writing an operating system in C, in the use of a few constants, the performance advantage of using const is minimal. Therefore, we use readonly instead of Const.