I have a 2013 iMac with a fixed disk, not an ssd. For unrelated reasons, I dual-boot it with two separate copies of macOS Catalina that share space in the same APFS container. Without knowing much about APFS, I was wondering if this could have an impact on the performance of the mac. Specifically, I was wondering if it could cause fragmentation of data across different physical sectors, thereby resulting in an increased need to seek from one place on the disk to another. Is this concern valid? Is it likely to cause any meaningful performance decrease, or has anyone else noticed one?