The == operator will compare for equality after doing any necessary type conversions. The === operator will not do the conversion, so if two values are not the same type === will simply return false. Both are equally quick.

For value types (numbers):
a === b returns true if a and b have the same value and are of the same type.

For reference types:
a === b returns true if a and b reference the exact same object.

For strings:
a === b returns true if a and b are both strings and contain the exact same characters.

Source: Stack overflow