The CLIC positron source is expected to produce and accelerate positrons up to 2.86 GeV. The optimisation of the positron source is an important task to fulfil the high-luminosity requirement with high-intensity positron beams and reduce the expected cost of construction and operation. In this study, we have improved the simulation and optimisation of the CLIC positron source. We developed a new simple and fast algorithm for a start-to-end positron source optimisation. A preliminary study of the mesh grid for the peak energy deposition density estimation based on simulation is also presented. The optimised CLIC positron source is expected to provide high positron yield while having the lowest cost at all energy stages.