Lowering cost by improving productivity is an important frontier for industrialisation of laser powder bed fusion (LPBF) additive manufacturing (AM). Use of high layer thickness process parameters is one particularly potent route to increase productivity while retaining the advantages of good metallurgical quality which are associated with LPBF. However, the effect of large layer thickness processing on certain critical material properties is not yet known. For materials such as Ni-base superalloys, high temperature performance is particularly crucial. This study therefore aims to better understand the effect of high layer thickness processes on high temperature performance of superalloys. Samples of two alloys, IN625 and HAYNES® 282®, were fabricated with conventional 40 µm and high-productivity 80 µm layer thickness process parameters. Defect distributions in the specimens were studied by X-ray Computer Tomography (CT) and the specimens’ microstructures, especially grain structures, were characterized with SEM-EBSD. The specimens were tested in stress rupture testing at temperatures in the range of 750°C to 950°C to characterize differences in performance. The observed differences in stress rupture performance were correlated to defect distributions and grain structures. The findings suggest that a trade-off in properties does exist when increasing productivity with 80 µm layer thickness processing, however the 80 µm processed materials can still meet requirements of commonly used material standards.