What is the speed of object comparison in a Set related to?

The comparison speed of objects in Set in Flutter (and in Dart in general) is directly related to the implementation of the hashCode and == methods for objects stored in the Set.

• hashCode: Set uses a hash table for efficient storage of elements. The hashCode method of an object is calculated to determine the "bucket" or "section" in the hash table where the object may reside. If two objects are considered equal (according to the == operator), their hashCode should match. Fast and correct calculation of hashCode for each object allows quick identification of potential matches in the hash table.
• == operator: After potential matches are found in one "bucket" of the hash table, the == operator is used for the final determination of whether the checked object is equal to the one already in the Set. If hashCode matches but the == operator returns false, it indicates a hash collision, and the Set continues searching in the same "bucket". A fast and precise implementation of == minimizes comparison time, especially when there are many elements with the same or similar hashCode.

If the hashCode and == methods are implemented incorrectly or are computationally expensive, the operation speed with Set (adding, removing, checking for presence) can significantly decrease. An ideal hashCode implementation distributes hashes evenly, minimizing collisions, which leads to an average operation complexity close to O(1). The == implementation should be consistent with hashCode and as fast as possible.