On Stratix 10 GX, running PCI Express example, is it normal to see much lower DMA write throughput than read throughput with default options?

I'm running the intel_fpga_pcie_link_test software, following all the steps in the Avalon-MM Intel Stratix 10 Hard IP+ for PCI Express document. When running option 0 - Run DMA, I see about 13 GB/se...