441213 - option to disable preloading of tabs opened in background

Status: RESOLVED DUPLICATE of bug 257453

(Firefox :: Tabbed Browser, enhancement)

Description

[Keith McAuley]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9) Gecko/2008052906 Firefox/3.0
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9) Gecko/2008052906 Firefox/3.0

Sometimes I have hundreds of tabs open. Seeing as I only have 512MB of RAM and half is already stolen by the OS, this is a problem. However, I use tabs in a very specific way: as a reading/reviewing queue. I have hundreds open, but I only use the first two or three on the very left, opening new tabs off of them and then closing the original tab, sort of maintaining a FIFO where tabs push onto the right and shift off the left. In this situation, I can solve all my memory woes, for myself and perhaps quite a few others, with a little optimization: create a method of opening tabs (via some combination of modifier keys and the mouse, or on the link context menu) that not only keeps the current tab focused, but doesn't actually attach a parsing or rendering state to the unfocused tab. In other words, the tab is simply a URL or a prefetched set of source code and images, left in an inactive and compressed form.

When the tab is first focused, the parser and renderer will fire off, throwing objects into memory, setting up a DOM, and uncompressing images for display, but until then, a tab that is "suspended" in such a way should occupy no more than a few kilobytes of memory.

In fact, if such a tab is focused but then unfocused again without any interaction to the tab's webpage on the user's part (that is, simply by being paged through along the tab bar), the rendering state can be thrown away again after the tab is unfocused (and perhaps a certain amount of time elapsed to guarantee that the user won't return.) Javascript onload and onmouseover handlers may pose a problem to the definition of "on the user's part", but it would be simple enough to say that any page with those handlers attached wouldn't unload once loaded.

Displaying such tabs a bit differently--say, with a "cryogenic" blue tint ;)--would be nice, but perhaps better left to an extension. There should be some means of identifying the tabs, both in the tab bar and tab dropdown list, though; it would be inconvenient, to sat the least, to be holding Ctrl+PgDn and then encounter an area of tabs that all act as if they were just opened when you encounter them.

Reproducible: Always

Steps to Reproduce:
1. Go to a site such as Wikipedia or Everything2--something deeply linked.
2. Start exploring, using only your middle mouse-button and the "close tab" button. Do not focus any tabs other than the first in your tab bar while doing this.
3. Repeat 2 until you have N tabs open, where N is such that Firefox takes up all of your computer's memory, and is well into your swap file.
Actual Results:  
Your computer will take 30-40 seconds to open a page, minutes to save the session to disk if you quit (and Firefox will continue to be open, working in the background for minutes, without any visual evidence to this fact), and perhaps up to half an hour to re-open from this saved session.

Expected Results:  
Firefox will respond almost exactly as if you had only one tab open, which, practically, you do.

Comment 1

[Jo Hermans]

see bug 141615 and bug 257453