Read performance - ok / optimal

I see there's another issue about read performance but that seems to be about a specific bug / environment so I'll create a new one.

Using M8 media in an HPE LTO8 autoloader, what is considered the best possible read performance currently? I'm seeing around 275-280 MB/s writes, which is very close to my raw tape speed, and 210 MB/s reads (+/- 10 MB/s). 210 MB/s is fine, but as always faster would be better. I'm using the latest master in Debian 10 on a xeon 2155 , 256 GB RAM and enterprise nvme drives. The files on the tape are 50-500 MB and I've tried using ltfs_ordered_copy and my own file copier with about the same result.

Is this the expected speed, or is there something I can do to improve it?