By default, Sass caches compiled templates and partials. This dramatically speeds up re-compilation of large collections of Sass files, and works best if the Sass templates are split up into separate files that are all @imported into one large file.
Without a framework, Sass puts the cached templates in the .sass-cache directory. In Rails and Merb, they go in tmp/sass-cache. The directory can be customized with the :cache_location option.
If you don’t want Sass to use caching at all, set the :cache option to false.
You can configure the Sass cache location by setting a Sass option in your compass configuration file like so:
sass_options = {:cache_location => "path\to\tmp\sass-cache"}
Source: Sass reference