CPU-Z Benchmarks on various Synology models - Hope this helps give a rough idea of the CPU power difference between models. Also included 2 other VMs running on Windows Hyper-V Server. :
Intel Xeon E5-2660 vs Intel Xeon E5-2690: What is the difference?
CPU Benchmarks - Intel Haswell-EP Xeon 14 Core Review: E5-2695 V3 and E5-2697 V3
Performance Comparison: E5-2690 vs E5-2687W | Puget Systems