Previous studies have shown the great potential, but also the great challenges, in handling slim reactors often used for polymerization reactions. Experiments and simulations were carried out in reactors with aspect-to-diameter ratios of up to 5, to test and to evaluate the mixing and dispersion efficiency for liquid-liquid systems of single-and multiple-stage impellers. Therefore, power consumption, mixing time and minimum dispersion speed were determined for five different stirrer types under turbulent conditions. It was found that the dimensionless mixing time is highly sensitive to the configuration of the impellers, with almost no dependency on the turbulent power number. Another focus was the analysis of the effect of the baffles. The influence of the baffle length in slim reactors on the mixing time and the macroscopic flow field was determined.