We covered PS4 External USB 3.0 HDD upgrade options, and recently Eurogamer tested some 4TB hard disk drives on the PlayStation 4 comparing their performance to SSD's in a USB enclosure. 
Check out the PS4 External Storage Loading Time Tests demonstration video below with some comparison charts as follows, to quote:
"Do you go for a large 4TB drive, or a fast SSD? Going into these tests, we decided to benchmark both of our options on both PlayStation 4 and PS4 Pro, as Sony's mid-gen console refresh can offer some small improvements on its own.
As testing progressed, a clear hierarchy of results began to roll in. The 4TB external drive actually improves loading times over PS4's regular drive, as well as having the advantage of offering more space.
As we know, PS4 Pro offers faster loading times on average anyway, compared to a regular PS4. The difference is slight on most games, but more pronounced with the likes of Pro-supported titles like Battlefield 1 and Skyrim. And as you can see from the table above, PS4 Pro certainly wins out on the stock side of the equation, no doubt.
The fact that we could increase storage massively by using a 4TB option while at the same time improving loading times is the icing on the cake.
Meanwhile, although performance is quite as fast using the USB hook-up, using an SSD still offers colossal improvements to loading times on many titles where loading is ponderous to say the least. It's been a long time coming, but we're happy to say that PS4's external storage functional fully delivers."
Check out the PS4 External Storage Loading Time Tests demonstration video below with some comparison charts as follows, to quote:
"Do you go for a large 4TB drive, or a fast SSD? Going into these tests, we decided to benchmark both of our options on both PlayStation 4 and PS4 Pro, as Sony's mid-gen console refresh can offer some small improvements on its own.
As testing progressed, a clear hierarchy of results began to roll in. The 4TB external drive actually improves loading times over PS4's regular drive, as well as having the advantage of offering more space.
| Base PS4 | Stock 5400rpm Internal Drive | Seagate 4TB External | OCZ 480GB SSD External | OCZ 480GB SSD Internal |
| Battlefield 1: Through Mud and Blood | 109.6 | 87.2 | 51.4 | 47.7 |
| Battlefield 1: The Runner | 70.2 | 54.4 | 33.0 | 31.5 |
| The Witcher 3: Novigrad | 95.6 | 87.7 | 77.1 | 69.2 |
| Fallout 4: Concord | 57.4 | 44.8 | 30.1 | 29.1 |
| Fallout 4: Exiting Vault 111 | 28.4 | 22.6 | 17.1 | 17.2 |
| Project Cars: Azure Coast | 44.4 | 41.4 | 40.3 | 40.4 |
| Skyrim: New Game | 22.1 | 18.6 | 15.1 | 16.7 |
| Skyrim: Loading to Helgen | 27.9 | 24.2 | 19.4 | 20.9 |
| Base PS4 vs Pro | PS4 Internal Stock | PS4 + External 4TB | PS4 Pro Internal Stock | PS4 Pro + External 4TB |
| Battlefield 1: Through Mud and Blood | 109.6 | 87.2 | 95.3 | 85.3 |
| Battlefield 1: The Runner | 70.2 | 54.4 | 60.0 | 53.5 |
| Skyrim: New Game | 22.1 | 18.6 | 19.0 | 16.8 |
| Skyrim: Loading to Helgen | 27.9 | 24.2 | 24.5 | 20.8 |
As we know, PS4 Pro offers faster loading times on average anyway, compared to a regular PS4. The difference is slight on most games, but more pronounced with the likes of Pro-supported titles like Battlefield 1 and Skyrim. And as you can see from the table above, PS4 Pro certainly wins out on the stock side of the equation, no doubt.
The fact that we could increase storage massively by using a 4TB option while at the same time improving loading times is the icing on the cake.
Meanwhile, although performance is quite as fast using the USB hook-up, using an SSD still offers colossal improvements to loading times on many titles where loading is ponderous to say the least. It's been a long time coming, but we're happy to say that PS4's external storage functional fully delivers."
