Traditionally, cellulosic materials have been applied in power transformers due to their good electrical insulation and oil absorption, although their hygroscopic characteristics consequently lead to time-consuming processes. Viewing to circumvent these limitations, the Additive Manufacturing of high-performance thermoplastics has been investigated as an alternative solution for solid insulation. In this context, the present work investigates the effect of process parameters on the geometrical and mechanical properties of 3D-printed Polyetheretherketone (PEEK) and Polyetherimide (PEI). To this end, the residual stresses and distortions are numerically computed considering different ranges of extrusion temperatures, printing speeds, and layer heights. Then, resulting elastic properties are predicted using the Asymptotic Homogenization technique. For that, two unit cells representing the microstructures found for the PEEK and PEI are adopted. From the obtained results, it was verified that lower layer heights and printing speeds, as well as higher extrusion temperatures, resulted in higher residual stresses. In contrast, higher layer heights, higher extrusion temperatures, and lower printing speeds resulted in higher distortions for both materials. In regards to the design of components, the obtained results provide useful data for both preliminary and critical analyses, potentially saving time and reducing waste of materials in future investigations involving 3D-printed high-performance thermoplastics.