From 6dda5c4963207d308464d54e9187a317bf344a6b Mon Sep 17 00:00:00 2001
From: Christopher Willis-Ford <7019101+cwillisf@users.noreply.github.com>
Date: Tue, 23 Feb 2021 11:26:00 -0800
Subject: [PATCH] use performance.mark to measure deserialize time

---
 src/virtual-machine.js | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/virtual-machine.js b/src/virtual-machine.js
index 5cec44c10..17440c736 100644
--- a/src/virtual-machine.js
+++ b/src/virtual-machine.js
@@ -478,6 +478,9 @@ class VirtualMachine extends EventEmitter {
         // Clear the current runtime
         this.clear();
 
+        if (typeof performance !== 'undefined') {
+            performance.mark('scratch-vm-deserialize-start');
+        }
         const runtime = this.runtime;
         const deserializePromise = function () {
             const projectVersion = projectJSON.projectVersion;
@@ -492,8 +495,14 @@ class VirtualMachine extends EventEmitter {
             return Promise.reject('Unable to verify Scratch Project version.');
         };
         return deserializePromise()
-            .then(({targets, extensions}) =>
-                this.installTargets(targets, extensions, true));
+            .then(({targets, extensions}) => {
+                if (typeof performance !== 'undefined') {
+                    performance.mark('scratch-vm-deserialize-end');
+                    performance.measure('scratch-vm-deserialize',
+                        'scratch-vm-deserialize-start', 'scratch-vm-deserialize-end');
+                }
+                return this.installTargets(targets, extensions, true);
+            });
     }
 
     /**