Network path conditions, such as loss, capacity, and delay, have a significant impact on the behavior and performance of networked applications. Path property emulators are essential and widely used tools to perform evaluations under realistic conditions. However, the quality of the emulation and the potential influence on experimental results itself is rarely considered. This work highlights how the performance limitations of existing tools, such as NetEm, a network emulator based on Linux traffic control, can alter network measurements. To address these shortcomings, we introduce MoonEm, a high-performance path property emulator based on the Data Plane Development Kit (DPDK). Moreover, we present a novel approach to precisely control packet transmission times on commodity hardware. MoonEm is focused on the emulation of realistic and reproducible network conditions. Our measurements demonstrate that MoonEm achieves a maximum packet rate of 13.39 Mpps compared to 0.98 Mpps for NetEm. In contrast to NetEm, we improve latency deviation from 71.15 µs to 53 ns for the median and from 769.26 µs to 80 ns for the worst case.