Websites that load slowly because they are poorly coded could soon be flagged by Google's Chrome browser.
Google said it was working on several "speed badging" systems that let visitors know why a page is taking time to show up.
The variations include simple text warnings and more subtle signs that indicate a site is slow.
No date has been given for when the badging system will be included with the Chrome browser.
In a blog, Google said it started the project to "to help users understand when a site may load slowly, while rewarding sites delivering fast experiences".
It said it was working on metrics that could spot when sites are "authored" in a way that makes them slow generally. The quirks of many web technologies make it easy for developers to code pages so they take a long time to appear.
In addition, pages are often slow to load because they are waiting for responses from off-site resources such as ad networks, social media widgets or code that analyses user behaviour.
Indicators could include text that says a page "usually loads slow" or might change the colour of a progress bar to hint that the page is a laggard.
In the blog, Chrome engineers said its plan to identify sites would be refined over time and was designed to improve the way websites were created.
"We are being very mindful with our approach to setting the bar for what is considered a good user experience and hope to land on something that is practically achievable by all developers," it said.
Google's Chrome browser is used by 64% of people who go online, figures from market research firm Statista suggest.
Google's plan was criticised on the Hacker News website, which is largely used by professional developers.
Some questioned how easy it would be to identify what causes pages to be slow. Many said pages were more likely to be slowed down by off-site ad networks than poor coding.
One commenter said the warnings would be seen as a "badge of shame".
He added: "What is fast depends on how the browser parses websites, so one website can be faster in Firefox but slower in Chrome, and still get a 'badge of shame'".