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One specific large Trello board suddenly becomes extremely slow on Windows

Oleksii
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I'm New Here
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August 25, 2026

Hello,

We are experiencing a recurring performance issue with one specific Trello board.

The board contains many cards, checklists, and attachments, so we understand that it is relatively heavy. However, its size has not changed significantly: it can work normally one day and become practically unusable the next. This has already happened several times over the past year, the issue appears, persists for some time, and then disappears without any changes on our side.

Current symptoms:

  • The board takes a very long time to load, freezes, and responds slowly.
  • Trello consumes up to approximately 7 GB of RAM.
  • The issue affects multiple users, not just one account or computer.
  • It occurs on Windows in both the web and desktop versions.
  • Other Trello boards work normally on the same computers.
  • The same problematic board appears to work normally on MacBooks.

We have already tried the standard troubleshooting steps: different browsers, incognito mode, clearing cache and site data, disabling extensions and Power-Ups, checking card covers, hardware acceleration, network connection, and the desktop application. None of these provided a stable solution.

Because the same board previously worked normally with approximately the same amount of data, we suspect a board-specific regression, client-side memory leak, or Windows/Chromium rendering issue rather than simply the number of cards.

Could the Trello/Atlassian team please investigate this board and check whether there are any abnormal API responses, problematic board data, rendering loops, or recent client-side changes affecting large boards on Windows?

We can provide the board URL/ID, browser console errors, HAR file, memory usage screenshots, affected account details, and reproduction steps privately.

2 answers

1 accepted

1 vote
Answer accepted
Andrea Crawford
Atlassian Team
Atlassian Team members are employees working across the company in a wide variety of roles.
August 26, 2026

@Oleksii Hi there! 

We identified a change that may have impacted performance on large boards in particular. That change has been rolled back, so I'm curious, is the issue better today after refreshing? 

Secondly, based on the boards associated with your account I think I can guess which board you're referring to (is it trello.com/b/U7V5dNH1 ? ). This board has over 27k attachments, which likely is responsible for some lag outside of any changes on our end. I can also see that 140+ new attachments were added in the last two weeks. While this may not be enough to cause performance issues across all devices, networks, and browsers, I have definitely seen before that when the amount of attachments gets this high, adding 100 more might be enough to cause a noticeable slowdown in some devices, networks, and browsers. Is it possible to archive some cards with attachments to get that number down lower?

I'm interested to know if the change roll back made a difference for you either way, and look forward to your response.

Oleksii
I'm New Here
I'm New Here
Those new to the Atlassian Community have posted less than three times. Give them a warm welcome!
August 27, 2026

Hi Andrea,

Thank you for your reply! Yes, we actually started noticing improvements just yesterday, and the Trello board is now working much better, essentially the way it used to.

I’m very glad to hear that you reverted the change you mentioned. We’ll also consider archiving our irrelevant cards and will check how everything works afterward.

Thank you very much for your response, and all the best!

0 votes
Arkadiusz Wroblewski
Community Champion
August 26, 2026

Hello and Welcome to Atlassian Community @Oleksii 

On Which Subscription Tier you are ? Free ? Standard ?

Best,

Arek🤠

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