Layout.reflow.async.duringDocLoad
Background
This preference affects the way a web page reflows (redraws itself) while loading.
When using synchronous reflow, Mozilla’s event loop blocks on all reflow events. In practical terms, this means that the UI can become inaccessible during the document load and some repaint events won’t fire. Asynchronous reflow solves this problem by limiting the maximum amount of time Gecko spends performing reflow events on each trip through the event loop and “posting” excess reflows to a queue to be processed on the next trip. This allows Mozilla’s event loop to proceed at a more predictable pace and keeps the UI responsive.
Possible values and their effects
True
Use asynchronous reflowing during document load. (Default)
False
Use synchronous reflowing during document load.
Caveats
- This preference does not exist by default. If it is not present, the code uses asynchronous reflowing.
- layout.reflow.timeslice must be a positive integer for this preference to work as designed.
- Setting this preference to false can result in buggy behavior; for this reason, the preference was removed from the Mozilla 1.9 trunk (i.e., Firefox 3.0).
First checked in
2000-09-12 by Nisheeth Ranjan.
Has an effect in
- Netscape (all versions since 6.0)
- Mozilla Suite (all versions since M18)
- Phoenix (all versions)
- Firebird (all versions)
- Firefox (all versions up to but not including 3.0a1)
- Minimo (all versions)
- SeaMonkey (all versions up to but not including 1.5a1)
Related bugs
- Bug 39368 - Enable async reflow processing during document load
- Bug 334543 - [FIX]Remove layout.reflow.async.duringDocLoad pref
