diff --git a/tracker/tracker/src/main/modules/img.ts b/tracker/tracker/src/main/modules/img.ts
index 1ca15e094..724fa0583 100644
--- a/tracker/tracker/src/main/modules/img.ts
+++ b/tracker/tracker/src/main/modules/img.ts
@@ -32,7 +32,24 @@ export default function (app: App): void {
     }
   }
 
-  const sendImgSrc = app.safe(function (this: HTMLImageElement): void {
+  const sendSrcset = function (id: number, img: HTMLImageElement): void {
+    const { srcset } = img
+    if (!srcset) {
+      return
+    }
+    const resolvedSrcset = srcset
+      .split(',')
+      .map((str) => resolveURL(str))
+      .join(',')
+    app.send(SetNodeAttribute(id, 'srcset', resolvedSrcset))
+  }
+
+  const sendSrc = function (id: number, img: HTMLImageElement): void {
+    const src = img.src
+    app.send(SetNodeAttributeURLBased(id, 'src', src, app.getBaseHref()))
+  }
+
+  const sendImgAttrs = app.safe(function (this: HTMLImageElement): void {
     const id = app.nodes.getID(this)
     if (id === undefined) {
       return
@@ -49,14 +66,8 @@ export default function (app: App): void {
     } else if (resolvedSrc.length >= 1e5 || app.sanitizer.isMasked(id)) {
       sendPlaceholder(id, this)
     } else {
-      app.send(SetNodeAttribute(id, 'src', resolvedSrc))
-      if (srcset) {
-        const resolvedSrcset = srcset
-          .split(',')
-          .map((str) => resolveURL(str))
-          .join(',')
-        app.send(SetNodeAttribute(id, 'srcset', resolvedSrcset))
-      }
+      sendSrc(id, this)
+      sendSrcset(id, this)
     }
   })
 
@@ -69,24 +80,26 @@ export default function (app: App): void {
           return
         }
         if (mutation.attributeName === 'src') {
-          const src = target.src
-          app.send(SetNodeAttributeURLBased(id, 'src', src, app.getBaseHref()))
+          sendSrc(id, target)
         }
         if (mutation.attributeName === 'srcset') {
-          const srcset = target.srcset
-          app.send(SetNodeAttribute(id, 'srcset', srcset))
+          sendSrcset(id, target)
         }
       }
     }
   })
 
+  app.attachStopCallback(() => {
+    observer.disconnect()
+  })
+
   app.nodes.attachNodeCallback((node: Node): void => {
     if (!hasTag(node, 'IMG')) {
       return
     }
-    app.nodes.attachElementListener('error', node, sendImgSrc)
-    app.nodes.attachElementListener('load', node, sendImgSrc)
-    sendImgSrc.call(node)
+    app.nodes.attachElementListener('error', node, sendImgAttrs.bind(node))
+    app.nodes.attachElementListener('load', node, sendImgAttrs.bind(node))
+    sendImgAttrs.call(node)
     observer.observe(node, { attributes: true, attributeFilter: ['src', 'srcset'] })
   })
 }
diff --git a/tracker/tracker/src/main/modules/longtasks.ts b/tracker/tracker/src/main/modules/longtasks.ts
deleted file mode 100644
index 2789aa99e..000000000
--- a/tracker/tracker/src/main/modules/longtasks.ts
+++ /dev/null
@@ -1,64 +0,0 @@
-import type App from '../app/index.js'
-import { LongTask } from '../app/messages.gen.js'
-
-// https://w3c.github.io/performance-timeline/#the-performanceentry-interface
-interface TaskAttributionTiming extends PerformanceEntry {
-  readonly containerType: string
-  readonly containerSrc: string
-  readonly containerId: string
-  readonly containerName: string
-}
-
-// https://www.w3.org/TR/longtasks/#performancelongtasktiming
-interface PerformanceLongTaskTiming extends PerformanceEntry {
-  readonly attribution: ReadonlyArray<TaskAttributionTiming>
-}
-
-export default function (app: App): void {
-  if (!('PerformanceObserver' in window) || !('PerformanceLongTaskTiming' in window)) {
-    return
-  }
-
-  const contexts: string[] = [
-    'unknown',
-    'self',
-    'same-origin-ancestor',
-    'same-origin-descendant',
-    'same-origin',
-    'cross-origin-ancestor',
-    'cross-origin-descendant',
-    'cross-origin-unreachable',
-    'multiple-contexts',
-  ]
-  const containerTypes: string[] = ['window', 'iframe', 'embed', 'object']
-  function longTask(entry: PerformanceLongTaskTiming): void {
-    let type = '',
-      src = '',
-      id = '',
-      name = ''
-    const container = entry.attribution[0]
-    if (container != null) {
-      type = container.containerType
-      name = container.containerName
-      id = container.containerId
-      src = container.containerSrc
-    }
-
-    app.send(
-      LongTask(
-        entry.startTime + performance.timing.navigationStart,
-        entry.duration,
-        Math.max(contexts.indexOf(entry.name), 0),
-        Math.max(containerTypes.indexOf(type), 0),
-        name,
-        id,
-        src,
-      ),
-    )
-  }
-
-  const observer: PerformanceObserver = new PerformanceObserver((list) =>
-    list.getEntries().forEach(longTask),
-  )
-  observer.observe({ entryTypes: ['longtask'] })
-}