Some containers are really inefficient when used with small payloads. For example std::set<void*> uses only 20% of its memory for the payload. See more details here: https://docs.google.com/document/d/1YL1FORFMWo0FK0lMg7WsImnjNQ3ZpY0nK0NHGjkeHT4/edit?usp=sharing

In some cases we can use "flat" containers that don't waste as much. One example is base::flat_set, which is drop-in replacement for std::set, and is more memory efficient.

It's counterpart flat_map is about to land (https://codereview.chromium.org/2715433007).
 

Some containers are really inefficient when used with small payloads. For example std::set<void*> uses only 20% of its memory for the payload. See more details here: https://docs.google.com/document/d/1YL1FORFMWo0FK0lMg7WsImnjNQ3ZpY0nK0NHGjkeHT4/edit?usp=sharing

In some cases we can use "flat" containers that don't waste as much. One example is base::flat_set, which is drop-in replacement for std::set, and is more memory efficient.

Companion flat_map container is about to land (https://codereview.chromium.org/2715433007).