Disclosed are embodiments of an adaptive enterprise service bus (ESB) runtime system and an associated method, which build, at a restart, only the most advantageous path configuration between composable units (e.g., between applications and/or between primitives within a single application). Specifically, during the execution of instantiations of modeled paths and branches thereof, metrics (e.g., the number of times each flow and each branch are activated, the CPU usage associated with building each flow and each branch, etc.) are collected. Then, at a restart of the runtime system, a cost-benefit analysis is performed on the collected metrics and, based on the results of this cost-benefit analysis, only selected ones of the paths and the branches thereof are built (e.g., paths and branches for which operational usefulness outweighs building costs). Other paths and branches are built only as required, during running of the runtime system.