cy.visit() performance degradation

[milankonir]

Current behavior

We're using Cypress to test large pages (several megs) and noticed severe performance degradation since upgrading to version 7.2.0. It takes over 20 seconds to visit the page. Majority of time is spent on TTFB. We have also noticed considerable increase in memory usage.

The problem persists with versions 7.3.0 and 7.4.0.

Loading the same page outside of Cypress automation takes fraction (~3 seconds) as the long TTFB period is not present

Desired behavior

Loading the page via cy.visit(); should take similar time (~3 seconds) as it does when visiting the page in browser and as it did prior to version 7.2.0.

Test code to reproduce

Fork with repro: https://github.com/milankonir/cypress-test-tiny

Screenshot from repro:

Versions

Affected versions: 7.2.0, 7.3.0, 7.4.0
Last working version: 7.1.0

[jennifer-shehane]

Yah, wow, I can reproduce this. Thanks for providing a reproducible example, this helps.

The site load event fires 20 seconds slower in 7.2.0 than in 7.1.0. I tracked this down to being introduced in #16113, where we downgraded electron. I had to pass in contextIsolation to get this commit to run, so I guess it's also possible that the contextIsolation change is the root cause: 48fe3fb It's weird because this issue isn't present in 7.0.1.

Issue not present: d4e4885
Issue present: 7b55863

7.1.0

7.2.0

[cypress-bot]

The code for this is done in cypress-io/cypress#17037, but has yet to be released.
We'll update this issue and reference the changelog when it's released.

[jennifer-shehane]

Reopening as we are reverting the previous PR to avoid possible performance implications for many users on low resources machines recording video. We'll continue investigating and hopefully move towards updating Electron to fix this issue.

[cypress-bot]

The code for this is done in cypress-io/cypress#17408, but has yet to be released.
We'll update this issue and reference the changelog when it's released.

[cypress-bot]

Released in 8.3.0.

This comment thread has been locked. If you are still experiencing this issue after upgrading to
Cypress v8.3.0, please open a new issue.