Rollup merge of #77233 - ssomers:btree_size_matters, r=Mark-Simulacrum
Rollup merge of #77233 - ssomers:btree_size_matters, r=Mark-Simulacrum

BTreeMap: keep an eye out on the size of the main components

r? @Mark-Simulacrum

graydon/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust