Update README.md

Author: matheus-git

README.md

@@ -46,14 +46,20 @@ if !tree.contains_key(&20) {
 
 ## Benchmark: flat_rbtree vs [rbtree](https://docs.rs/rbtree/latest/rbtree/) (10,000 operations)
 
-> Since all operations are at most O(log n), this benchmark is just to give an idea of the performance compared to a pointer-based implementation.
-
 | Operation | flat_rbtree | [rbtree](https://docs.rs/rbtree/latest/rbtree/) |
 |-----------|----------------|---------------|
 | **Insert** | 1.14 ms   | 1.34 ms  | 
 | **Remove** | 2.12 ns        | 354 ps       | 
 | **Search** | 655 µs         | 514 µs       | 
 
+## Benchmark: `flat_rbtree` vs [`BTreeMap`](https://doc.rust-lang.org/std/collections/struct.BTreeMap.html) (10,000 operations)
+
+| Operation | `flat_rbtree`          | `BTreeMap`             |
+|-----------|------------------------|-------------------------|
+| **Insert** | 1.14 ms  | 0.89 ms  |
+| **Remove** | 2.12 ns              | 18.9 µs                 |
+| **Search** | 702 µs                 | 524 µs                  |
+
 
 ## 📝 License