Wouldn't surprise me if it was a combination between size of games and HDD limitations.
When you write to a HDD that 10GB game is spread across the disk and the fuller the disk the longer it takes to search especially as you erase old and write new content to it. That's why defragmintation always made a computer faster it would place parts of a singe program/file next to each other on a HDD.
Because of SSD's taking over the performance segments (even £300 laptops come with 128GB SSD's now) HDD's are focusing on capacity at the expence of performance which is fine for external HDD's but not so good for consumer electronics like game consoles.







