Firefox 1.5 front-to-back performance improvement function based on user behavior research results

Memory issues in Firefox 1.5


One complaint from people after upgrading from Firefox 1.0 to 1.5 is memory issues. On this matter, on February 2, the following mozillaZine  came up on

Firefox Chief Engineer Ben Goosercompared to Firefox 1.0 on their blog An article explaining why memory usage increased in Firefox 1.5wrote Ben admitted that there are memory leaks in all versions of Firefox, while pointing out that many people confuse memory leaks with increased memory usage. Firefox 1.5 remembers the contents of the most recently used pages up to 8 pages, depending on the amount of memory in the system. Disabling this feature reduces memory usage, but instead increases page load times when performing backward/forward commands.

Original text: MozillaZine: Ben Goodger Explains Higher Memory Usage in Firefox 1.5




The increase in memory usage in Firefox 1.5 is due to the ability to save web pages backwards and forwards rather than because of memory leaks.

Reading Ben Gooser's article, the increase in memory usage in Firefox 1.5 is not entirely due to a memory leak in Firefox. All software can have memory leaks, and Firefox has the same problem, and experts say it has been fixed. The increase in memory usage is because up to 8 web pages are stored in the memory when the web page is forward or backward.

In addition, since Firefox uses tab navigation, it saves 8 pages for each tab, so memory usage is inevitably large.

When I open a PowerPoint file with an embedded Excel file in Office 12, which I have been using since last year, I am experiencing a phenomenon that even virtual memory runs out, but I have never experienced a memory shortage due to Firefox while using Firefox 1.5.



Web page forward and backward functions in Firefox 1.5 use memory

One of the features of Firefox 1.5 ( is that the page loads faster than in 1.0 when the browser's one page back and one page forward buttons are clicked. will become

Performance and Accessibility

  • Improved performance with a next-generation rendering and layout engine that speeds navigation between previously viewed Web pages through intelligent caching and displays complex Web pages more accurately.

When the 1.5 spec first came out, I never thought that it would be stored in memory. However, as the rendering technology improved, I thought it would be better to render faster. However, through this announcement, it seems that up to 8 pages of visited pages are stored in the memory, so when you click the forward or back button, it appears to be displayed quickly.



To turn this feature off

Enter about: config in the browser's address input window, and change the browser.sessionhistory.max_total_viewers set to -1 to 0.



39% of the pages people navigated to
Mainly using the back button Revisit the 10 most recently visited pages

Firefox 1.5 used the following research results to determine the web page forward and backward caching capabilities. I wanted to see the full text of the study, but I couldn't find it. If anyone knows, please let me know. Once I put it in Ben Gooser's comment. When people visit a web page, 39% of the pages they visit say that they use the back button to revisit the last 10 pages they visited.

studies show that 39% of all page navigations are renavigations to pages visited < 10 pages ago, usually using the back button




Because people use the back button to navigate web pages, the fast-loading forward/backward function was determined

At first, when I saw this content, I read it out of curiosity because people raised a lot of memory problems on the Korean Mozilla forum ( If you look at the discussion on Ben Roger's blog, there are many articles about Opera and IE 7 and comparison.

However, while reading Ben Gooser's article, I was surprised that the fast forward and backward navigation function of Firefox 1.5 was determined by the user's behavior data, even though it was a product made by programmers rather than technical aspects.


To improve performance when navigating (studies show that 39% of all page navigations are renavigations to pages visited < 10 pages ago, usually using the back button), Firefox 1.5 implements a Back-Forward cache that retains the rendered document for the last few session history entries. This can be a lot of data. It's a trade-off. What you get out of it is faster performance as you navigate the web.

Studying user behavior and creating solutions to overcome the phenomenon or problem is a difficult task. No, it is difficult to recognize the problem.

Firefox 1.5's front-back performance improvement function seems to me to be remembered as an example of function exposure to solve user problems using user behavior data rather than memory leaks.


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