How to not freeze render loop when doing heavy operations

[Panuchka]

Just a quick question; how to not freeze the render loop when doing "heavy" operations?

Example:
In my game, I have a stage that is composed of squares. The player can move around the stage but so can the enemies. The enemies are using a pathfinding system that uses navigation mesh. This navigation mesh is created dynamically when the game runs.
Player can destroy the tiles of the stage. The tile destruction triggers the recalculation of the navmesh. The recalculation itself is a pretty heavy operation that freezes the whole game for a second or so.

What I'm pretty much asking is if there is an async functionality for heavy functions/operations that are triggered from the render loop. Or what is the best way to handle these situations?

[jerome]

webworkers ?

[davrous]

Yes the only option is Web workers 

[adam]

Does the pathfinding system freeze the game when there is only one enemy using it?  

If not, I'd simply limit the amount of times you can call the pathfinding function per frame.

edit:

OK, I'm seeing that just the recalculation of the navmesh freezes the game.  You probably are going to need to use webworkers.