A device for optimising the use of resources on a computing infrastructure, the computing infrastructure including one or more computing structures hosting a plurality of application building blocks (2a, 2b, 2c, 2d), said device including: - a storage module able to store a plurality of repositories including: ∘ a management capacity repository configured to store at least two time periods associated with different resource requirements, ∘ an application profile repository configured to store data for identifying the computing structure(s) used by an application building block and a piece of data corresponding to a criticity indicator of said application building block, ∘ a computing infrastructure repository configured to store characteristics of server resources for at least one computing structure of the computing infrastructure, said characteristics of server resources including a piece of data of evolution rules as well as a piece of data corresponding to an evolution complexity indicator, ∘ an available resource repository configured to store characteristics of available resources, said characteristics of available resources including available amount data as well as a piece of data corresponding to a complexity indicator for making the resource available, and ∘ an execution rule repository configured to store data corresponding to maximum resource use levels; - a load planning module able to calculate, for a time period, from the data of the management capacity repository and the application profile repository, levels of resources required; - a module for selecting computing structures configured to, from the required resource levels calculated and data of the computing infrastructure repository and from the available resource repository, select computing structures required for the time period; and - an optimisation module configured to generate, from the selection of computing structures required for the time period and data of the execution rule repository, at least one placement plan including data of computing structures to be used and at least one evolution plan listing modifications of resources to be made. - a storage module able to store a plurality of repositories including: ∘ a management capacity repository configured to store at least two time periods associated with different resource requirements, ∘ an application profile repository configured to store data for identifying the computing structure(s) used by an application building block and a piece of data corresponding to a criticity indicator of said application building block, ∘ a computing infrastructure repository configured to store characteristics of server resources for at least one computing structure of the computing infrastructure, said characteristics of server resources including a piece of data of evolution rules as well as a piece of data corresponding to an evolution complexity indicator, ∘ an available resource repository configured to store characteristics of available resources, said characteristics of available resources including available amount data as well as a piece of data corresponding to a complexity indicator for making the resource available, and ∘ an execution rule repository configured to store data corresponding to maximum resource use levels; ∘ a management capacity repository configured to store at least two time periods associated with different resource requirements, ∘ an application profile repository configured to store data for identifying the computing structure(s) used by an application building block and a piece of data corresponding to a criticity indicator of said application building block, ∘ a computing infrastructure repository configured to store characteristics of server resources for at least one computing structure of the computing infrastructure, said characteristics of server resources including a piece of data of evolution rules as well as a piece of data corresponding to an evolution complexity indicator, ∘ an available resource repository configured to store characteristics of available resources, said characteristics of available resources including available amount data as well as a piece of data corresponding to a complexity indicator for making the resource available, and ∘ an execution rule repository configured to store data corresponding to maximum resource use levels; - a load planning module able to calculate, for a time period, from the data of the management capacity repository and the application profile repository, levels of resources required; - a module for selecting computing structures configured to, from the required resource levels calculated and data of the computing infrastructure repository and from the available resource repository, select computing structures required for the time period; and - an optimisation module configured to generate, from the selection of computing structures required for the time period and data of the execution rule repository, at least one placement plan including data of computing structures to be used and at least one evolution plan listing modifications of resources to be made.