diff --git a/node-health/src/readiness.ts b/node-health/src/readiness.ts
index ed3d357..9f55399 100644
--- a/node-health/src/readiness.ts
+++ b/node-health/src/readiness.ts
@@ -28,8 +28,11 @@ export type ReadinessResult = {
 
 /** Detail of an individual readiness check */
 export type ReadinessDetail = {
+	/** Name of the readiness check */
 	name: string;
+	/** Status of the readiness check */
 	status: ReadinessStatus;
+	/** Optional message providing additional information about the readiness check */
 	message?: string;
 };
 
@@ -40,6 +43,7 @@ export type ReadinessDetail = {
  */
 export const readiness = async (checks: ReadinessFunction[]): Promise<ReadinessResult> => {
 	const start = Date.now();
+	const t0 = performance.now();
 	const details: ReadinessDetail[] = [];
 
 	for (const check of checks) {
@@ -55,7 +59,7 @@ export const readiness = async (checks: ReadinessFunction[]): Promise<ReadinessR
 		}
 	}
 
-	const duration = Date.now() - start;
+	const duration = performance.now() - t0;
 
 	return {
 		status: aggregateStatus(details.map((d) => d.status)),