Use _.throttle like normal people would.

package.json

@@ -22,6 +22,7 @@
     "web-ext": "^1.9.1"
   },
   "dependencies": {
+    "lodash": "^4.17.5",
     "webextension-polyfill": "^0.1.1"
   },
   "browserify": {

src/content_script.js

@@ -1,4 +1,5 @@
 import browser from 'webextension-polyfill'
+import throttle from 'lodash/throttle'
 
 function hideBanners() {
   const revertSteps = []
@@ -50,14 +51,10 @@ function hideBanners() {
 function main() {
   let state = 'off'
   let revertSteps = []
-  let lastRun
 
   function onScroll(event) {
     let action
-    if (window.scrollY > 20 &&
-      (state === 'off' || (state === 'on' && event.timeStamp - lastRun > 1000))
-    ) {
-      lastRun = event.timeStamp
+    if (window.scrollY > 20 && (state === 'off' || state === 'on')) {
       state = 'starting'
       action = () => {
         revertSteps = hideBanners().concat(revertSteps)
@@ -76,7 +73,7 @@ function main() {
     }
   }
 
-  window.addEventListener('scroll', onScroll)
+  window.addEventListener('scroll', throttle(onScroll, 1000))
 }
 
 main()