Guest domains (virtual machines) may execute at a virtualization server. During execution, the guest domains may request various services to facilitate their operation. The virtualization server may disaggregate the services requested by the guest domains among various service domains. A service domain may be configured to provide one the services. The virtualization server may also maintain a pool of partially initialized service domains. When a guest domain requests a particular service, one of the partially initialized service domains may be selected from the pool, and the partially initialized service domain may complete initialization to become an initialized service domain. The initialized service domain may thus be configured to provide the service requested by a guest domain. The virtualization server may periodically replenish the pool of partially initialized service domains to ensure that a partially initialized service domain is available upon demand from one of the guest domains.