Bitbucket webpage is very slow on Firefox

[Hieu Phan]

I am the admin for my Bitbucket instance. Recently, a few Firefox users came to me about long loading times when navigating Bitbucket. It would be slow to access Bitbucket, logging in, navigating the project pages, etc...  Our users access Bitbucket via a VPN connection to our enterprise network (Palo Alto Networks GlobalProtect). 

I can replicate this issue on Firefox 78.0.2 on Win10 64bit.

Here is a screenshot of the Firefox dev console showing the loading time: 

• This issue can only be replicated on Firefox. 
• This issue only occurs when accessing Bitbucket over our VPN.
• This issue does not occur when accessing Bitbucket on-site. 
• This issue does not occur on other web browsers (Chrome, IE, Edge)
• This issue does not occur on our other Atlassian hosted apps (Jira, Confluence, Bamboo).

Things I have tried:

• Disabling all Firefox add-ons/plugins
• Running Firefox in safe mode
• Clearing Firefox cache/cookies

Any thoughts on this odd issue? 

[Hieu Phan · Accepted solution]

Disabling DNS over HTTPS (DoH) on Firefox fixed the issue for us. We have a special DNS setup with an external and internal record. Our external record points to a NAT address but can only be accessed from a certain site. Our internal record is mainly what's used for regular users. DoH was resolving to the external record first which caused the poor performance. 

A Homer Simpson D'OH moment for me. 

[Michael McQuary]

> This issue only occurs when accessing Bitbucket over our VPN.

Just noting that I am not using a VPN, yet encountered slowness in certain sections of Bitbucket to the point of it being unusable along with errors.  Turning off DoH massively improved performance.  Thanks!