Investigate and improve browser Total Blocking Time (LCP) performance of View File (source) page into S2 tier
The View File (source) page's browser Largest Contentful Paint (LCP) performance is significantly unperformant:
NAME | FCP (ms) | LCP (ms) | TBT (ms) | SI (ms) | LVC (ms) | TFR SIZE (kb) | SCORE | RESULT
--------------------------------------|----------|------------------|------------------|---------|----------|---------------|-------|-------
web_project_file_source | 942 | ✘ 42217 (<11500) | ✘ 38770 (<8500) | 2494 | 42200 | 753.5 | 75 | FAILED
The View File (source) page being tested can be seen here on Staging. This page is specifically one loading in a large source file.
Of note this page appears to have significantly deteriorated recently as up until Friday last week (2021-04-16) it was recorded as having a LCP of around 12 seconds.
This looks to be all on the Browser side as the server performance has remained consistent throughout.
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 LCP metrics is above the target of 9000 ms which is severity1 . Task is to improve the page's browser performance into S2 tier and investigate its dependence on Google Chrome version.