What is the difference between map before Go 1.24 and after?

Before version Go 1.24, the built-in map type had certain limitations and implementation features that affected performance and behavior:

• The internal structure of the map was less optimized, which could lead to more collisions and rehashing.
• Some improvements in memory management and hashing algorithms were absent.

In Go 1.24, a significant overhaul of the map implementation was carried out:

• The performance of insert, search, and delete operations was improved.
• Memory usage was optimized, reducing the number of allocations.
• Resistance to collisions and rehashing was enhanced.

These changes made working with maps more efficient and predictable, especially in scenarios with a large number of elements or high contention.

Details can be found in the Go 1.24 release notes and the runtime source code.