Shared electronic resources can be allocated for a gaming application on a dynamic basis. A package of game content and configuration can be used to allocate an appropriate amount of resource capacity. Task-based instances can be launched as needed and terminated once a gaming session has completed. In order to account for relatively long load times, a number of pre-warmed task-based instances can be allocated that can load the game server functionality up to a determined state. The number of pre-warmed instances can be based on a number of different factors, such as an amount of unused capacity across a shared resource environment. When a request for a session is received, a pre-warmed instance is selected to be upgraded to a game server instance to serve the game session for the request. Pre-warmed instances can be reclaimed if capacity is needed for other purposes.