PostHog app consuming excessive browser memory tabs in background

TL;DR

What fixed it Fixed by the PostHog team: they reorganized how the app and the posthog-js SDK deal with localStorage, massively reducing both the frequency and the size of each localStorage write, which avoids triggering the underlying Chromium bug.

Steps

1. What was going on

Users reported the PostHog web app consuming excessive browser memory, with memory accumulating while tabs sit in the background and dropping when the tab is reopened. No concrete reproduction steps and not linked to any browser extension. Investigation traced it to how often and how much the app and the posthog-js SDK write to localStorage, which triggered a Chromium bug (crbug 351244335).

2. What fixed it

Fixed by the PostHog team: they reorganized how the app and the posthog-js SDK deal with localStorage, massively reducing both the frequency and the size of each localStorage write, which avoids triggering the underlying Chromium bug. PostHog-js PRs #3721 and #3727 shipped the new defaults behind the SDK side. Reports stopped after the fix. If you run an older posthog-js, upgrade to pick up the reduced-write behavior.

When to use

You are seeing this: What was going on Users reported the PostHog web app consuming excessive browser memory, with memory accumulating while tabs sit in the background and dropping when the tab is reopened. Use this skill when you run into "PostHog app consuming excessive browser memory tabs in background".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

In the thread, the question was: Users reported the PostHog web app consuming excessive browser memory, with memory accumulating while tabs sit in the background and dropping when the tab is reopened. No concrete reproduction steps and not linked to any browser extension. Investigation traced it to how often and how much the app and the posthog-js SDK write to localStorage, which triggered a Chromium bug (crbug 351244335). The verified resolution: Fixed by the PostHog team: they reorganized how the app and the posthog-js SDK deal with localStorage, massively reducing both the frequency and the size of each localStorage write, which avoids triggering the underlying Chromium bug. PostHog-js PRs #3721 and #3727 shipped the new defaults behind the SDK side. Reports stopped after the fix. If you run an older posthog-js, upgrade to pick up the reduced-write behavior. Thread: https://vectle.com/threads/thrht8I3qswKkieq9-XazB8g