Improve browser Total Blocking Time (TBT) performance of Merge Request Changes page into S3 tier
Merge Request Changes page's browser Total Blocking Time (TBT) results are unperformant:
* Environment: 10k
* Environment Version: 15.10.0-pre `d244fd30a63`
* Date: 2023-03-06
NAME | FCP (ms) | LCP (ms) | TBT (ms) | SI (ms) | LVC (ms) | TFR SIZE (kb) | SCORE | RESULT
--------------------------------------|----------|----------------|-----------------|---------|----------|---------------|-------|-------
web_project_merge_request_changes | 1678 | ✓ 5266 (<9300) | ✓ 6267 (<22000) | 3603 | 10300 | 1574.2 | 68 | Passed
Old data from 2021-10-22
Update from 2021-10-22: However looking at the latest month's metrics, the results degraded - TBT results range from 8700ms up to 13200ms.
One of the examples of the recent massive failure:
* Environment: 10k
* Environment Version: 14.4.0-pre `8e1dff81ae4`
* Date: 2021-10-21
NAME | FCP (ms) | LCP (ms) | TBT (ms) | SI (ms) | LVC (ms) | TFR SIZE (kb) | SCORE | RESULT
--------------------------------------|----------|-----------------|------------------|---------|----------|---------------|-------|-------
web_project_merge_request_changes | 1432 | ✓ 4844 (<6500) | ✘ 11818 (<10000) | 2561 | 7017 | 1127.9 | 69 | FAILED
The Merge Request Changes page being tested can be seen here on Staging. This page shows changes that are being added in merge request.
Test Details
Testing was done on our 10k Reference Architecture environment with our lab condition SiteSpeed pipeline (named GitLab Browser Performance Tool internally). The project being tested is a copy of gitlabhq (tarball can be found here). GitLab Browser Performance Tool tests information is listed at Current test details page.
The latest GitLab Browser Performance pipeline results can always be found here. Through this page the full SiteSpeed report can be found via the SiteSpeed Report
link on that page.
As per our performance targets this page's TBT metric is above the target of 2000 ms which is severity2 . Task is to improve the page's browser performance into next tier.