Something like this should work:
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I did some tests a while back and 100Mbps "Fast" Ethernet does make a difference.

These tests were from/to my Raspberry Pi 4 "retro home server" running
MacIPRpi (1Gbps Ethernet) with both the PM 6500/275 and the Pi connected via an Apple Airport Extreme 6th Generation's Gigabit capable Ethernet ports. The software used was Newer Tech "Performance" v1.3 which is included in their
EtherTech 1.5 installer.
The driver I used ("Apple Enet" extension, v2.4.2) for the "Apple Fast Ethernet 10/100BaseT Card" didn't work under Mac OS 7.6. For the "AsanteFast 10/100 PCI Ethernet Adapter Rev. B" I used
this driver from Macintosh Garden.
The hard drives I used for the different OS tests were different which makes the tests not directly comparable but I was testing with what I had on hand and as much as it bothers me that I didn't take the time to get a disk configured with partitions for each OS and run the tests from there I think it does help illustrate the impact of drive performance on network data transfers.
My take aways:
Mac OS 7.6, and likely earlier versions, aren't really able to take advantage of 100Mbps Fast Ethernet. Not sure about 8/8.1 but by 8.5/8.6 it seems Apple made OS changes which allow the same hardware and driver (the Asante card/driver being the proof) to take advantage of 100Mbps Fast Ethernet.
In testing and real world you need to have source and destination disks able to sustain more than 10Mbps (1.25MBps) reads and writes to make use of 100Mbps Fast Ethernet. The "RAM to Server" tests may likely show some SD card storage bottlenecks on my Raspberry Pi server.