N8n UI Execution Delay with Large Loops – Mail Sent Before UI Updates

Questions
1

Hi everyone,

I’ve been experiencing an issue where the n8n UI execution status lags behind the actual workflow execution when handling large loops. Here’s the situation:

  • My workflow processes an array with multiple iterations, checking conditions in a loop.
  • If a condition is met, it triggers a Mail node to send an email.
  • However, during execution, I noticed that the UI still shows the Mail node as “Waiting to execute…”, while I’ve already received the email.
  • Only after the entire workflow finishes running does the UI update and show the Mail node as .success

Possible Cause (My Assumption)

I suspect that the large number of iterations in the loop causes excessive UI updates (node animations, progress updates), which results in UI rendering delays. Meanwhile, the backend executes much faster than what the UI can display.

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Information on your n8n setup

  • n8n version: 1.82.3
  • Database (default: SQLite):
  • n8n EXECUTIONS_PROCESS setting (default: own, main):
  • Running n8n via (Docker, npm, n8n cloud, desktop app): Docker
  • Operating system: Windows11
2

HI @estsaiDev

Welcome to the community!

When running large executions doing so via the UI is not a good idea.
n8n needs to send all data to your browser as well which is quite slow. the new canvas did improve, but it is still an issue with large data sets.
Best is to run things like this in the background.
You can easily do this by adding a schedule for a certain time it needs to run. Or by adding a webhook or form for example to trigger the flow. make sure to set the flow active and use the production url though, otherwise it is still executing in the UI.

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