G-Drive USB (6 TB) - Different partition disk speeds

Using the MacOS High Sierra Disk Utility, I just reformatted my 6 TB G-Drive USB hard drive into 3 partitions. Once I did so, I checked the disk speed of each partition using Blackmagic Disk Speed Test. Unfortunately, the 3 partitions have very different disk speed benchmarks (tests repeated many times):

Partition #1 = 4 TB (210-220 MB/s)
Partition #2 = 1 TB (150-170 MB/s)
Partition #3 = 1 TB (120-130 MB/s)

The speed noted for Partition #1 is close to what was advertised for this device (226 MB/s).

Is this speed degradation expected when this drive is partitioned like this? If not, what am I doing wrong and how can I correct this situation?

Thank you,

I noticed the same thing when partitioning my 6TB as 4TB and 2TB. The 2TB benchmark is 150-170 Mbps. Cannot answer your question as to why.