Good and Evil C# functions in the view of performance

Good:

Here are some C# functions that are commonly used for system performance improvement:

1. StringBuilder: StringBuilder is used to efficiently concatenate strings. It avoids the memory allocation overhead of creating a new string every time you concatenate two strings.
2. String.Format: This function is used to efficiently format strings by using a format string and a list of arguments. It avoids the overhead of repeatedly concatenating strings.
3. Parallel.For and Parallel.ForEach: These functions are used to run loop iterations in parallel, allowing you to utilize multiple cores to improve performance.
4. System.GC.Collect: This function is used to explicitly run the garbage collector. It can help improve performance by freeing up memory that is no longer being used by your application.
5. MemoryCache: This class is used to cache data in memory. It can improve performance by avoiding the overhead of repeatedly fetching data from disk or from a database.
6. StreamReader and StreamWriter: These classes are used to efficiently read from and write to streams. They can improve performance by reducing the number of disk or network I/O operations needed to read or write data.
7. Task.Run: This function is used to run an asynchronous operation in the background. It can help improve performance by allowing your application to continue running while the task is running in the background.
8. lock statement: The lock statement is used to synchronize access to a shared resource. It can help improve performance by avoiding race conditions and deadlocks.

Evil:

Here are some examples of C# functions that can be bad for performance:

1. string.Concat: This function can be slow because it creates a new string each time you concatenate two strings. This results in multiple memory allocations and can lead to memory fragmentation.
2. string.Replace: This function creates a new string every time it’s called, which can be slow when used frequently.
3. Array.Copy: This function can be slow because it copies elements one by one, rather than using a more efficient block copy operation.
4. Thread.Sleep: This function can cause performance issues by blocking a thread for a specified amount of time. This can result in reduced responsiveness and slow performance.
5. String.IsNullOrEmpty: This function can be slow because it creates a new string every time it’s called.
6. Linq.ToList: This function can be slow because it creates a new list every time it’s called. It also materializes the entire list, which can be slow and consume a lot of memory if the list is very large.
7. Reflection.GetProperties: This function can be slow because it uses reflection to inspect the properties of an object. Reflection can be slow because it has to inspect the type information at runtime, rather than at compile-time.