Load Background Tabs Lazily EN

This extension tries to duplicate some of the behavior of Load Tabs Progressively, an add-on that has not been updated to work with newer versions of Firefox.

Load Background Tabs Lazily places newly created background tabs in a line and allows only a specific number to load, while blocking the rest. A tab is removed from the line once it has finished loading. The first blocked tab in the line is then allowed to load. This extension was designed for users with slow internet connections that routinely open multiple background tabs at the same time. It also helps users that open many background tabs at once by not overwhelming their browser or CPU.

Only tabs with http(s) URLs are blocked from loading by this extension. In many cases, the URL to be loaded in a new tab can't be viewed by this extension when the tab is created and added to the line. Tabs with non-http(s) URLs that were added to the line will quickly be removed when the URL is viewable.

Various commands or settings for the extension can be accessed in the toolbar button popup or in its Options page.

Chrome version: https://chrome.google.com/webstore/detail/load-background-tabs-lazi/jomliinifiaagjbbjncdncgoolfiakjj

Read Before Installing

Before adding this extension or after installing it, do not select 'Run in Private Windows'. This extensions Options page will open to the 'Permissions' section after installing. A user must select the 'Access your data for all websites' permission for this extension to function. Once the permission is granted, this extension may be turned on by clicking its toolbar button and selecting the 'Turn Off or On' command. The 'Access your data for all websites' permission allows this extension to block almost any http(s) URL from loading. As this is not a 'Recommended' (manually reviewed) extension, granting this permission is a security risk. This extension is best used in a profile or a non-private window where data loss like passwords or personal info would not be very damaging, in case of rogue behavior.

If 'When you open a link, image or media in a new tab, switch to it immediately' is unselected in Firefox's Settings page, a mouse middle click on a web page link will create a new tab in the background. Otherwise, a shift middle click can be used to create a background tab. A bookmark opened in a new tab is not loaded in the background by default. A preference to reverse that behavior is in the about:config page:

• browser.tabs.loadBookmarksInBackground (Control behavior of new tabs opened from bookmarks and history.)
  • true: Load the tab in the background.
  • false (default): Load the tab in the foreground.

If that setting is changed to true, a mouse middle click will open a bookmark in a new tab in the background. Otherwise, a shift middle click must be used.

Conflicting Extensions

HoldTab, LoadTabOnSelect, LoadTabOnSelect Evolution, LoadTabOnSelect 3, Load Background Tabs on Select, and Load Tabs Sequentially. These are extensions that block new background tabs from immediately loading.

Temporary Containers. The conflict happens when a blocked background tabs hostname is a match under Temporary Containers 'Per Domain Isolation'.

Issues/Limitations

For Firefox desktop only. Not for Android.

Current versions of Firefox have Fission (site isolation) enabled ( https://wiki.mozilla.org/Project_Fission ). Fission was enabled by default in Firefox 97 (Feb 2022). Be aware that when opening a lot of non-discarded tabs with different domains, memory usage may increase significantly due to Fission. Even if a new background tab is blocked from loading, memory may still be allocated for site isolation. Fission also increased the time it takes to open large groups of non-discarded tabs. For example, opening and blocking 1000 tabs may take around 5 seconds on a browser with Fission disabled, but may take around 15 seconds when enabled. Note, the more tabs that exist in a window (even if many are hidden tabs), the longer it takes to create a new group of tabs in that window.

It is recommended to open no more than 250-500 non-discarded background tabs at one time with Fission enabled. The browser may even crash when opening groups of 1000 or more non-discarded tabs. How many non-discarded tabs that can be safely opened at once often depends on a users computer. If creating more than 250-500 tabs at once, they should probably be created in a discarded (unloaded) state.

This extension does not work on restricted sites (addons.mozilla.org, support.mozilla.org, etc).

Ideally, all blocked tabs should be loaded before Firefox is exited or restarted. The title of a blocked tab that is recovered after a previous session is restored is blank or 'New Tab'.

Blocked tabs that are removed from the line before they have loaded can't be added back to the line if this extension is turned off or if the tabs are restored. Please select the option 'Update new background tabs to placeholder tabs after blocking them from loading', if this is a concern.

This extension does not block duplicate tabs or closed tabs that are reopened.

Sometimes a tab will …