There is also another potential factor that you ignored. If your internet connection is somehow throttled, it would definitely be much slower. In addition, if your internet is slow, that can be a bottleneck. Bitcoin Core is also heavily reliant on the disk speed. If your read/write speeds are slow, it would also be a bottleneck.
No, no, my internet has been neither throttled, nor slow.
The only potentially possible bottleneck related to my computer could have been hard disk read/write operations (as it was a usual 7200 rpm hdd, not an SSD). But! At a moment (when the downloaded blockchain data had not exceeded 32Gb) I tried to move the data directories to a fast USB 3.0 flash card (exactly to find what was the bottleneck).
The syncing did become a little bit faster indeed. But Not significantly!