Your iMac is capable of tens of thousands of io per second if you bring fast storage to it, internally or externally so your wish can be granted, just not with HDD. In the end, connect an SSD via thunderbolt if you need equivalent speeds to having an internal SSD on an iMac. Some HDD add a layer of SSD and try to cache data similar to how Apple does Fusion drives (think nitrous oxide), but this doesn’t get you NVMe. Boot to the fastest SSD connected via NVMe controller for max performance and speed, there is no shortcut, especially with a truck response and SATA driving. You want a light car running on gas to get the best acceleration. Diesel fuels most trucks and some cars (computer “fuel” is SATA interface and command set).You can’t make a truck operate like a car unless you buy a car and call it a truck.
