Generating a single sprite/image from a group?

[Jikmo]

I'm using Lewster's Isometric plugin to draw a floor made out of tiles that a character will walk over.

 

However, it's very slow and pointless to redraw each tile every frame since the tiles aren't changing in any way.  Also, they aren't being used in the physics engine, so it doesn't make sense to keep them as individual tiles.  Is there any way to turn a group of sprites into a single sprite or image?

[Jikmo]

Lewster helped me in another thread.  He said to set the group's "cacheAsBitmap" property to true.