Higher Capacity Hard Drives Stay Faster
Higher capacity hard drives are faster as they fill up as compared to smaller ones, because for the same amount of data, the data is stored on the faster part of the drive.
See Larger Hard Drives Are Faster Than Smaller Ones and Why You Need More Space Than You Need.
This graph shows what happens as the drives of various sizes are filled with 1TB of data, as tested with DiskTester, your best testing tool for understanding and testing drive performance and reliability.
Click the graph to read more.
Here’s another take, using the average speed for 1TB of data on different capacities: