Why Does Scrolling Up Skip Messages in Channels sometimes?

Problem

Some users have noticed that when scrolling upward to view past messages in a channel, the view may jump further back in history than expected, skipping several lines of conversation.

• Frequency: Often noticeable in channels with many messages
• Impact: Users may need to scroll back down to reach the desired point in history
• Environment: Seen in both the desktop app and web browser

Cause

This behavior happens due to the way Mattermost handles large message histories.
Mattermost uses a technique called virtualized scrolling, which keeps performance fast and smooth, even in channels with tens of thousands of messages.

Instead of loading every single message at once, Mattermost loads only the ones you can see on screen (plus a small buffer above and below). This means:

• Performance remains excellent, even in very large channels.
• Occasionally, when scrolling quickly, the system may miscalculate the position and appear to jump further back in history.

This is expected behavior by design, not a bug.

Solution / Workarounds

If you encounter this issue:

1. Scroll more slowly when navigating through older messages.
2. Use the search feature (Ctrl + F or Cmd + F) to find specific messages without scrolling.
3. Try a different browser, as the scrolling experience may vary.

This scrolling behavior is part of how Mattermost is designed to ensure fast performance in large channels. While it may feel unexpected at times, it is normal and can be managed with the workarounds above.