1. A system operative to execute efficiently a plurality of actions, comprising: a first compute element; a cache memory belonging to the first compute element; and a first data set associated with a first data source; wherein the system is configured to: fetch the first data set from the first data source to the cache memory; execute, in the first compute element, as directed by a first application program running on the first compute element, and in conjunction with the first data set now in the cache memory, a first action involving said first data set; identify, within a second application program, a second action that, like the first action, involves the first data set; and instruct the first compute element, after said execution of the first action and while the first data set is still in the first memory, to: at least temporarily halt execution of the first application program, while leaving the first data set in the cache memory; and temporarily execute the second application program, at least until the second action is performed by the second application program in conjunction with the first data set still in the cache memory, thereby avoiding a need to re-fetch the first data set.