Techniques for reducing the startup latency of functions in a Functions-as-a-Service (FaaS) infrastructure are provided. In one set of embodiments, a function manager of the FaaS infrastructure can receive a request to invoke a function uploaded to the infrastructure and can retrieve information associated with the function. The retrieved information can include an indicator of whether instances of the function may be sticky (i.e., kept in host system primary memory after function execution is complete), and a list of zero or more host systems in the FaaS infrastructure that currently have an unused sticky instance of the function in their respective primary memories. If the indicator indicates that instances of the function may be sticky and if the list identifies at least one host system with an unused sticky instance of the function in its primary memory, the function manager can select the at least one host system for executing the function.