Query optimizations

There are some tricks to consider when using the SQL API that might make your application a little faster.

Only request the fields you need. Selecting all columns will return a full version of your geometry in the_geom as well as a reprojected version in the_geom_webmercator.
Use PostGIS functions to simplify and filter out unneeded geometries when possible. One very handy function is, ST_Simplify.
Remember to build indexes that will speed up some of your more common queries.
Use cartodb_id to retrieve specific rows of your data, this is the unique key column added to every CartoDB table.