add bbox_cache to doc-string
@@ -94,6 +94,10 @@ class Frontend:
ctx: the properties relevant to rendering derived from a DXF document
out: the backend to draw to
config: settings to configure the drawing frontend and backend
+ bbox_cache: bounding box cache of the modelspace entities. This can
+ speed up paperspace rendering, because each VIEWPORT entity has to
+ process the whole modelspace. By passing the bbox cache the
+ frontend can filter entities which are not visible in the VIEWPORT.
"""
