I'm new to Open Street Map and PostGIS, and am trying to figure out how to find all of the ways that intersect a linestring (i.e. all of the streets that intersect a route). Is there a way to do this that doesn't involve calling ST_Intersects on every row of the table?
What you are looking for is only checking for intersecting within a bounding box. See: Selecting by bounding box with PostGIS