diff --git a/routes/_utils/marks.js b/routes/_utils/marks.js
index 83a4527..5614767 100644
--- a/routes/_utils/marks.js
+++ b/routes/_utils/marks.js
@@ -1,25 +1,26 @@
-import noop from 'lodash/noop'
+import { thunk } from './thunk'
 
-const enableMarks = process.browser &&
+// Lazily invoke because URLSearchParams isn't supported in Edge 16,
+// so we need the polyfill.
+const enabled = thunk(() => process.browser &&
   performance.mark &&
-  (process.env.NODE_ENV !== 'production' ||
-  new URLSearchParams(location.search).get('marks') === 'true')
+  (
+    process.env.NODE_ENV !== 'production' ||
+    new URLSearchParams(location.search).get('marks') === 'true'
+  )
+)
 
 const perf = process.browser && performance
 
-function doMark (name) {
-  perf.mark(`start ${name}`)
+export function mark(name) {
+  if (enabled()) {
+    perf.mark(`start ${name}`)
+  }
 }
 
-function doStop (name) {
-  perf.mark(`end ${name}`)
-  perf.measure(name, `start ${name}`, `end ${name}`)
-}
-
-const mark = enableMarks ? doMark : noop
-const stop = enableMarks ? doStop : noop
-
-export {
-  mark,
-  stop
-}
+export function stop(name) {
+  if (enabled()) {
+    perf.mark(`end ${name}`)
+    perf.measure(name, `start ${name}`, `end ${name}`)
+  }
+}
\ No newline at end of file
diff --git a/routes/_utils/thunk.js b/routes/_utils/thunk.js
new file mode 100644
index 0000000..bd15a80
--- /dev/null
+++ b/routes/_utils/thunk.js
@@ -0,0 +1,11 @@
+export function thunk(fn) {
+  let value
+  let called
+  return () => {
+    if (!called) {
+      value = fn()
+      called = true
+    }
+    return value
+  }
+}
\ No newline at end of file
diff --git a/templates/main.js b/templates/main.js
index a745c0d..18a2b0c 100644
--- a/templates/main.js
+++ b/templates/main.js
@@ -6,6 +6,7 @@ import '../routes/_utils/historyEvents'
 import '../routes/_utils/loadingMask'
 
 loadPolyfills().then(() => {
+  console.log('init()')
   // `routes` is an array of route objects injected by Sapper
   init(document.querySelector('#sapper'), __routes__)
 })