Young woman with her hands up in frustration with a Macbook laptop

Your Mac only has a finite amount of memory available, so if a process starts to use more than its fair share, the rest of the system can suffer. Sometimes, Safari will warn you that a website is using a lot of memory, but what can you do about it and how do you stop it from coming back?

What the “Significant Memory” Warning Really Means

Your computer uses physical memory, or RAM (random access memory), to store data that needs to be rapidly accessed by the system. The more memory you have, the longer you can go before running out. To make the most of available memory, the solid-state drive is used as a temporary location to “swap” data in and out as required, which is why a Mac with twice as much memory isn’t necessarily twice as capable.

macOS Activity Monitor Memory Overview

Some websites require more system resources than others. This is often the case with complex websites like social media feeds or web applications like Google Docs which handle a lot of data. There also may be scripts running in the background of a webpage that introduce additional overhead.

The “significant memory” warning is an indicator that a tab is asking for a lot of system resources, which may lead to a performance drop. More memory being used by one process means there is less memory available to the system overall. This can result in slowdowns, crashes, and instability.

An example of Safari's "Significant Memory" Usage Error Caused by Gmail

This warning will only appear above the tab causing the issue, so you may need to cycle through tabs if you suspect a web page is causing your computer to perform poorly.

Things You Can Try That May Help

The easiest remedy is to refresh the tab in question. This should force Safari to reallocate resources, freeing up any memory that’s tied down and removing the warning. Unfortunately, a problematic website is likely to keep asking for more resources and so the warning can come back.

Safari splits tabs up by process in Activity Monitor (accessible via Spotlight or under Applications > Utilities). Access the “Memory” tab then arrange the “Memory” column by descending to see which processes are using the most memory at the top. You can quit any webpage process to force a reload.

Managing Memory Usage in Activity Monitor for macOS

You can take the more drastic route of quitting Safari altogether (using Command+Q or simply right-clicking on the dock in the icon). If Safari has become unresponsive you may need to force quit the process to restore performance.

Sometimes warnings such as these can be caused by problems rendering a webpage as a result of an outdated browser. Install any available updates for Safari under System Preferences > Software Update is recommended for both performance and security reasons.

If the website in question has an issue with Safari in particular, installing and using a second browser like Chrome or Firefox could be the answer. Safari is a solid choice for Mac users on account of being highly optimized, but it often doesn’t enjoy the same support as more popular cross-platform browsers.

If you’re seeing this error a lot, you might want to consider upgrading your Mac. If your machine is relatively new, it’s likely a problem with the website and you may want to submit a support ticket or seek an alternative. Accessing the website periodically rather than leaving it open all of the time could work too.

Ditch Plugins and Extensions to Speed Up Safari

Webpages using more than their fair share of resources is an issue that appears from time to time, but there may be more you can do to improve Safari’s performance across all websites.

Consider ditching web plugins and removing unnecessary browser extensions to reduce Safari’s overall footprint, freeing up more resources for thirsty webpages and other processes.

Profile Photo for Tim Brookes Tim Brookes
Tim Brookes is a technology writer with more than a decade of experience. He's invested in the Apple ecosystem, with experience covering Macs, iPhones, and iPads for publications like Zapier and MakeUseOf.
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