Inconsistency in Performance between New and Old Issue View

Atlassian update:
Enhancing the page load performance is in our priority list and we are working to at least reach parity with the old issue view and then enhance it further, however, the journey is not easy and we are delivering outcomes iteratively. Please keep an eye on this ticket to learn about our progress and we shall share our shipped improvements as it becomes available

Issue Summary

It is worth noting that a lot of Performance issues tends to rise in and out of using Jira's Old and New Issue view. All these may be as a result of many of factors, however there's some particular behaviour that occurs sparingly for some users whereby out of a sudden Jira New Issue view tends to become slower compared to the Old Issue view, sometimes it happens in reserve etc.

Environment

Jira Cloud

(If Applicable view Point)

• Project view
• Issue View
• Board View

Steps to Reproduce

1. login to your instance https://<your-instance>.atlassian.net
2. Navigate to a Project
3. Try to view an Issue within that Project or from the Board view, given that you have the most basic filter e.g. project = ABC ORDER BY Rank DESC

Expected Results

Navigating to an issue should render quickly in a considerable amount of time e.g. https://<your-instance>.atlassian.net/browse/ABC-123 within 4-5 seconds and should be consistent as that page is being cached.

Actual Results

Navigating to an issue tends to be slow, in some cases it might be a basic issue and the load time tends to be longer e.g. https://<your-instance>.atlassian.net/browse/ABC-123 ranging from 10 seconds or > 20 seconds even though the page has been visited all over with CPU thread increasing especially when multiple tabs are concurrently opened.

Notes

Due to this inconsistency, in some cases, the slowness are actually the same across issue view (new and old). First of all when an issue is loaded "the issue title and description are loaded first nearly instantly, but the sections for comments and everything else are loading for a few seconds. And while they are loading CPU usage jumps to 100% and on the Dev console you can notice too many "long running task" being captured with difference ranging from ms to seconds.

Other examples, lies with the Browser being used - you can notice that in some instances, Chrome tends to consume more CPU thread than Firefox. When loading a simple issue, the CPU thread can spike up really fast especially when multiple tabs are running and the issue that are opened contains an attachment.

Explaining further this factor, out of the many request that are being called when the issue view is loading, they encounter latency, buffering, congestion etc that causes the Javascript resources to pause and block, making it seem like a Javascript issue when in reality it is not, resulting in the pages load taking much longer than usual.

In some situation The TTFB (Time to First Byte) values might be quite low towards a fully loaded page which might take up to 20 seconds and you might see some Javascript and CSS resources that took 4-5 seconds and they are only 100KB-800KB sizes files.

Workaround

This behaviour seems to vary

• In some conditions, switching to the New Issue View becomes faster to render a page (Probably due to SPA and SSR working in pairs)
• In some other conditions, switching to the Old Issue View seems faster to load or have no performance related issues at all.
• Other conditions, would be having a Quad Core device rather than a Dual Core device.(based on CPU thread spiking sparingly at various intervals)
• Changing Browsers (From Chrome to Firefox) might alleviate the situation