![\"PerfCompare](\"http:\/\/blog.mozilla.org\/performance\/files\/2026\/09\/simpleview-1000x532.png\")
<\/p>\nWe heard you. You don\u2019t want to open your PerfCompare performance comparison and feel like you need a background in statistics to interpret the Mann-Whitney-U results. Cliff’s Delta, CLES, and normality tests, oh my! It should not feel like you\u2019ve blindly walked into a college stats exam, unless of course, you love statistics. For the rest, all you want is an easy answer to the question: Did my changes make things faster or slower?<\/p>\n
So we fixed that. PerfCompare now shows the bare essentials by default and tucks the heavy statistics one click away.<\/p>\n
The results table now leads with the platform, the Base and New values, how far the median moved and its direction, the status (which includes the option to filter out noise) and the size of the change. To create a more advanced view, a single \u201cAdvanced options\u201d dropdown allows you to add the expert columns (Cliff\u2019s Delta, CLES, Significance) and the info-rich expanded row details below the full-width graph. A small help section at the top of the results provides a quick explanation of the columns. The purpose is to serve a diverse audience while preserving your selections in the URL so a shared link reproduces your view.<\/p>\n
<\/p>\n
The \u201cAdvanced options\u201d dropdown lets you add the precise statistics columns:<\/p>\n
Each one toggles on independently, so you can surface only Significance or the whole trio.<\/p>\n
![\"PerfCompare](\"http:\/\/blog.mozilla.org\/performance\/files\/2026\/09\/Screenshot-2026-09-03-at-11.26.06-1000x613.png\")
<\/p>\n
Expand a result and you get a clean panel: a full-width graph of how your Base and New runs are spread out, a quick summary (platform, app, which direction is “better”), and a little “how to read this graph” tool-tip for anyone who hasn’t stared at a distribution curve before. You can still poke at the graph’s mode controls if you want to dig in.<\/p>\n
![\"PerfCompare](\"http:\/\/blog.mozilla.org\/performance\/files\/2026\/09\/Screenshot-2026-09-02-at-15.19.48-1000x657.png\")
<\/p>\n
You can access the extra expanded row details such as effect size and confidence intervals or the full stats table in the \u201cAdvanced options\u201d dropdown. Turn on what you need, and the expanded extras lay out in neat two-column rows. If you turn on mode analysis and there aren’t multiple modes to show, we now say “No mode analysis available” instead of a blank space.<\/p>\n
Lastly, the advanced columns and expanded-row details you’ve switched on, along with your filters and sorting, are all encoded in the URL. Paste it to a coworker and they’ll land on the same result you were looking at; for filters and sorting, the shared link takes precedence over whatever they had saved locally. (One exception: the “How to read the results” panel is a personal per-browser preference, so it stays with you rather than tagging along on the link.)<\/p>\n
Several follow-ups on the way:<\/p>\n
We want PerfCompare to work for all users, whether you’re chasing your first regression, or you\u2019re an expert who doesn\u2019t want to lose their favorite metrics to a cleaner view. Our answer is separating the simple view from the power user view, and making the toggle obvious and shareable.<\/p>\n
The great news is it\u2019s live now! Go expand a Mann-Whitney-U result, click around the Advanced options, and tell us what you think. Please share your feedback, suggestions, or comments on the #perfcompare channel on Matrix<\/a>. If you’ve encountered a bug or have a feature request, please file them in Bugzilla<\/a>. We\u2019re listening.<\/p>\n","protected":false},"excerpt":{"rendered":" We heard you. You don\u2019t want to open your PerfCompare performance comparison and feel like you need a background in statistics to interpret the Mann-Whitney-U results. Cliff’s Delta, CLES, and … Read more<\/a><\/p>\n","protected":false},"author":1994,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"_links":{"self":[{"href":"https:\/\/blog.mozilla.org\/performance\/wp-json\/wp\/v2\/posts\/580"}],"collection":[{"href":"https:\/\/blog.mozilla.org\/performance\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.mozilla.org\/performance\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.mozilla.org\/performance\/wp-json\/wp\/v2\/users\/1994"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.mozilla.org\/performance\/wp-json\/wp\/v2\/comments?post=580"}],"version-history":[{"count":0,"href":"https:\/\/blog.mozilla.org\/performance\/wp-json\/wp\/v2\/posts\/580\/revisions"}],"wp:attachment":[{"href":"https:\/\/blog.mozilla.org\/performance\/wp-json\/wp\/v2\/media?parent=580"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.mozilla.org\/performance\/wp-json\/wp\/v2\/categories?post=580"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.mozilla.org\/performance\/wp-json\/wp\/v2\/tags?post=580"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}