You can minimize the amount of memory XP Server uses by unloading a DLL from XP Server memory after the ESP request that loaded it terminates. To do so, set esp unload dll so that the DLLs are automatically unloaded when ESP execution finishes. If esp unload dll is not set, you can free DLLs explicitly by using sp_freedll.
You cannot unload DLLs that support system ESPs.