CHAR vs VARCHAR in terms of performance

CHAR, NCHAR    
- fixed type: the system always allocates the indicated size in memory.
- UPDATEs don't need data shifting or physical row expansion.
- If frequent UPDATES operation is anticipated for a column, CHAR/NCHAR types is preferred.

 VARCHAR, NVARHCAR   
- variable type: the system allocates variable size in memory depending on size of the value.
- Less storage is used
- Thus, the less there is for a query to read.
- Faster query performance.