Is a hash map always constant time? When might it be slightly more?

A hash map (map) in Go typically provides insert, search, and delete operations in amortized constant time O(1). However, in some cases, the time can increase:

• Hash collisions: If many keys hash to the same bucket, operations can degrade to linear time proportional to the number of elements in that bucket.
• Reorganization (resize): When a certain load factor is reached, the hash map increases its internal array, which requires redistributing elements — temporarily increasing operation time.
• Poor hash function: If the hash function distributes keys unevenly, it will increase the number of collisions.

Thus, on average, operations are fast, but in the worst case, the time can be more than constant.