A container is an isolated run-time environment. It contains all the dependencies (configuration files, binaries, system libraries, code, etc.) that it needs to run your workflows smoothly. Due to this container, the differences in OS distributions as well underlying infrastructure are eliminated. This allows Built.io Flow to run on all the systems in a standard manner.
The size of the container determines the execution speed of your workflows. The bigger the size, the better the speed. While the available container sizes, as of now, is 256 MB, 512 MB, and 1024 MB, you will soon be able to choose from more size options. To view or change your existing container size, go to 'Workflow Settings > EXECUTION SETTINGS'.