CrystalDiskMark
We have a three-year old Synology DS418 serving as a direct comparison, and while the older unit is both capable and compatible with the latest release of DiskStation Manager, the Intel Celeron J4125 at the helm of the DS920+ fares better in CrystalDiskMark's demanding 4KQ32 test.
Given the nature of the benchmark, performance isn't increased through the use of an SSD cache, and the numbers are right where we expect them to be as we're effectively saturating the 1GbE link. Users with a managed switch may be able to double sequential performance through link aggregation, but in mid-2020 we feel any NAS product in the region of £500 ought to feature 2.5GbE connectivity as a minimum.