Firefox Running Slow Or Freezing? Here's What To Do

With so many options available, choosing a web browser can be tough  Even if you narrow it down to the 10 major choices, you might get stuck choosing between a few. For me, the problem was deciding whether I should go with Chrome or Firefox. Then I decided to do both. For a variety of reasons, but mostly wanting to keep work and my personal life separate — Chrome is what I use for stuff like what you're reading now, and Firefox is where I shop, socialize, and watch YouTube videos. Not all of the tools I use for work function properly in Firefox, but Chrome isn't exactly one of the most private web browsers, hence the split.

The downside to all of this is that one of Firefox's biggest problems — and one of the primary reasons people stop using it — is memory usage. It's a bit of a resource hog, which is made even worse due to my tendency to keep multiple tabs open (sometimes using between 200 to 300 MB of memory each). Tabs that are usually full of YouTube videos I intend to watch later, and the platform does not play nice with the browser's ad blocker. It hasn't for some time, and the company's latest pushback against them suggests this isn't changing any time soon.

Eventually, Firefox starts to slow down — tabs take a while to load or even scroll through. And if the downturn goes on for long enough, the browser can stop functioning entirely and even temporarily bog down my MacBook's general performance. When that happens, I fall back on a couple of methods to get things running properly again.

Since this particular brand of slowdown and freezing is a matter of memory, the best way to deal with it is to free up some of said memory. Closing out excessive tabs definitely helps, since each one draws on at least a little bit of memory even if it's not currently in use (even Mozilla acknowledges this). Another "trick" that sometimes works for me when it's specifically a YouTube tab being fussy is to reload the tab. If this doesn't get things moving again, I'll copy the tab's URL from the address bar, close it, then paste the URL into a new tab. Shuffling around tabs isn't always enough, though, in which case I'll quit Firefox entirely — sometimes resorting to pressing Command + Option + Esc to force quit if it's totally frozen. As a bonus, Firefox defaults to downloading and installing new updates in the background, so if the slowdown is the result of an outdated browser, closing and reopening it will take care of that, too.

Shutting off extensions can also help, though rather than turning everything off all at once, I'll type "about:processes" into the address bar to pull up Firefox's current memory usage. The list includes a relatively handy "Extensions" category with a summary of how much space each program is taking up. From here, you can decide whether it's worth the effort of turning them all off.

Short of switching to a different browser, which I don't want to do, my last resort is to replace the "places" database. However, it's a last resort for a reason: It houses browsing history, bookmarks, and other retained information. So of course replacing it clears all of that out, and I'm not a big fan of having to restore or recover my bookmarks, retrain Firefox to recognize the non-bookmarked sites I frequent the most, and so on. But when things get really bad, and nothing else is helping, it's worth a shot.

Start by clicking on the "Help" option at the top of the screen and select "More Troubleshooting Information" to pull up a new Firefox tab. Scroll down the "Application Basics" list and find the "Profile Folder" section, then click the "Show in Finder" button to open the folder through your desktop. Now, and this is very important — quit Firefox before attempting to do anything else. Depending on the operating system, the necessary files may be sitting right there in the opened folder. For me, though, I have to go one layer deeper into the "default-release" folder (it displays an alphanumeric string of characters, but ends with "default-release"). 

From here, find the file labeled "places.sqlite" (if it exists, also look for "places.sqlite-journal"). Rename the file (or files) by adding an extra word to the end of the default name — this prevents continued use from Firefox and also lets you mark the older and possibly corrupted file (Mozilla suggests something like "places.sqlite.old," but it doesn't have to be "old"). Reopen Firefox and the browser will create a replacement "places" file (or files). Assuming the places database was the cause of all those performance issues, this should get things running more smoothly again.

While it's irritating but not impossible to deal with memory-related slowdown or freezing, I find it's usually easier to try and avoid the issue entirely. Mozilla claims that hardware acceleration improves performance, but this isn't the case for every setup. Shutting it off is a simple matter of opening Firefox's Settings (click "Firefox" and select "Settings"), the scrolling down to the "Performance" section toward the bottom and un-checking "Use recommended performance settings" and "Use hardware acceleration when available." Afterward, restart Firefox. 

Keep in mind that hardware acceleration conflicts are allegedly tied to the machine's GPU and drivers, so turning the process off isn't a guaranteed fix. But if nothing changes or performance gets worse, you can repeat these steps to turn it back on again. It mostly comes down to moderation and paying attention. As long as you don't let too many memory-heavy tabs stew for too long and give Firefox a chance to rest (even for a few minutes), you should be able to avoid any major performance hiccups.