1. A system for providing low-latency computational capacity from a virtual compute fleet, the system comprising: an electronic data store configured to store at least a program code of a user; and a virtual compute system comprising a plurality of virtual machine instances usable to execute one or more program codes thereon on a per-request basis, the virtual compute system comprising one or more hardware computing devices configured to execute specific computer-executable instructions, the virtual compute system in communication with the electronic data store and configured to at least: maintain a first subset of the plurality of virtual machine instances in a warming pool comprising virtual machine instances to be assigned to a user and having one or more software components loaded thereon and a second subset of the plurality of virtual machine instances in an active pool comprising virtual machine instances assigned to one or more users; receive a request to execute a program code associated with a user on the virtual compute system, the request including information usable to identify the program code and the user associated with the program code, wherein the program code is associated with configuration data indicating at least a first portion of the program code to be executed with a trusted credential and a second portion of the program code to be executed without the trusted credential; select from the warming pool or the active pool a virtual machine instance to be used to execute the program code; create a first container in the selected virtual machine instance to execute the first portion of the program code with the trusted credential; create a second container in the selected virtual machine instance to execute the second portion of the program code without the trusted credential such that both of the first container and the second container are created in the selected virtual machine instance, wherein the second container is configured to communicate with the first container; cause the first portion of the program code associated with the user to be loaded from the electronic data store onto the first container in the selected virtual machine instance and executed in the first container with the trusted credential; and cause the second portion of the program code associated with the user to be loaded from the electronic data store onto the second container in the selected virtual machine instance and executed in the second container without the trusted credential.