All USB-to-Ethernet adapters are pretty evil in my experience. Always terrible performance, often slower than WiFi.
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I use 2.5 GbE USB adapters and they work great... as long as they're in the right port.
Half of the ports on my Thunderbolt dock are provided by a shaky ASMedia USB chipset and it drops or lags after an hour or so. The other half of the ports use a more solid Fresco Logic chipset and I left an iperf + ping running overnight and it was a solid 2.3 Gbit 0.x ms the whole time. The built-in Apple ports are also solid.