Agree. Even if the hash map somehow wouldn't use more than an array[256], it would still be faster as the compiler can optimize more due to simpler memory layou

Agree. Even if the hash map somehow wouldn't use more than an array[256], it would still be faster as the compiler can optimize more due to simpler memory layout, and even the cpu can cache more efficiently and better speculate since less/simpler code is involved. Always start with an array if the problem allows for it, even if you need to reallocate sometimes, or have to scan linearly. Measure performance before using a map or linked list.