diff --git a/src/vs/editor/common/model/bracketPairColorizer/concat23Trees.ts b/src/vs/editor/common/model/bracketPairColorizer/concat23Trees.ts
index 8fb21788fde..1756fa9e577 100644
--- a/src/vs/editor/common/model/bracketPairColorizer/concat23Trees.ts
+++ b/src/vs/editor/common/model/bracketPairColorizer/concat23Trees.ts
@@ -8,6 +8,8 @@ import { AstNode, ListAstNode } from './ast';
 /**
  * Concatenates a list of (2,3) AstNode's into a single (2,3) AstNode.
  * This mutates the items of the input array!
+ * If all items have the same height, this method has runtime O(items.length).
+ * Otherwise, it has runtime O(items.length * max(log(items.length), items.max(i => i.height))).
 */
 export function concat23Trees(items: AstNode[]): AstNode | null {
 	if (items.length === 0) {
diff --git a/src/vs/editor/common/model/bracketPairColorizer/nodeReader.ts b/src/vs/editor/common/model/bracketPairColorizer/nodeReader.ts
index af56e6deba4..cc938d38b15 100644
--- a/src/vs/editor/common/model/bracketPairColorizer/nodeReader.ts
+++ b/src/vs/editor/common/model/bracketPairColorizer/nodeReader.ts
@@ -24,6 +24,7 @@ export class NodeReader {
 
 	/**
 	 * Returns the longest node at `offset` that satisfies the predicate.
+	 * Has runtime O(log n) where n is the number of nodes in the tree.
 	 * @param offset must be greater than or equal to the last offset this method has been called with!
 	*/
 	readLongestNodeAt(offset: Length, predicate: (node: AstNode) => boolean): AstNode | undefined {