@aHguf5QP Did you try running top and xentop from the host command line to see about resource utilization (CPU and memory), as well is iostat to look at the storage I/O resource utilization? It may take more memory and/or CPU cores for dom0.
Some of slowness can be from lack of resources, some can be inherent in the storage (RAID configuration, connectivity bottlenecks, buffer and other settings, etc.). If this is a single SSD drive then you're at the mercy of what the controller and drive itself can manage on the storage end, but there may be system settings that could help.
Just 4 cores and 8 threads is not much for running a server, plus you didn't mention what the clock speed is, which also factors in quite a bit in performance.