Wiznet chips W5100, W5200 and W5500 are automatically detected.
Efficient block mode of W5200 & W5500 are used for data and multi-byte register access.
Wiznet socket registers are cached, which greatly reduces SPI communication overhead, at the cost of a small increase in RAM usage. TCP connections and UDP packets accessed in small chunks typically see a substantial performance boost.
Adafruit's Ethernet.init(CSPIN) extension is supported, to allow use of different pins for the chip select signal. Optimized direct register I/O is used for most Arduino compatible boards.
http://www.pjrc.com/teensy/td_libs_Ethernet.html
| Board | Chip | Shield / Module | Internet | Local (LAN) |
|---|---|---|---|---|
| Teensy 3.6 | W5500 | WIZ850io | 212.59 | 1143.58 |
| Teensy 3.6 | W5200 | WIZ820io | 202.44 | 1102.71 |
| Teensy 3.6 | W5100 | WIZ812MJ | 180.76 | 274.14 |
| ESP32 Feather | W5500 | Featherwing Ethernet | 211.06 | 965.76 |
| Teensy 3.2 | W5500 | WIZ850io | 205.37 | 958.06 |
| Teensy 3.2 | W5200 | WIZ820io | 215.44 | 914.78 |
| Teensy 3.2 | W5100 | WIZ812MJ | 170.07 | 234.55 |
| ChipKit Uno32 | W5500 | Seeed Ethernet W5500 | 177.19 | 858.81 |
| ChipKit Uno32 | W5200 | WIZ820io | 188.31 | 837.56 |
| ChipKit Uno32 | W5100 | Ethernet R2 (clone) | 159.72 | 272.18 |
| Arduino Due | W5500 | Seeed Ethernet | 214.44 | 689.69 |
| Arduino Due | W5200 | WIZ820io | 206.51 | 670.88 |
| Arduino Due | W5100 | Arduino Ethernet R3 | 105.98 | 109.73 |
| ESP8266 Feather | W5500 | Featherwing Ethernet | fail (dns) | 583.31 |
| Teensy LC | W5500 | WIZ850io | 200.51 | 479.73 |
| Teensy LC | W5200 | WIZ820io | 199.62 | 471.95 |
| Teensy LC | W5100 | WIZ812MJ | 126.40 | 137.77 |
| Arduino 101 (Intel) | W5500 | Seeed Ethernet W5500 | 168.96 | 359.32 |
| Arduino 101 (Intel) | W5200 | WIZ820io | 169.37 | 349.35 |
| Arduino 101 (Intel) | W5100 | Arduino Ethernet R3 | 42.39 | 43.60 |
| Teensy 2.0 | W5100 | WIZ812MJ | 81.07 | 84.85 |
| Arduino Uno R3 | W5500 | Seeed Ethernet W5500 | 185.44 | 329.00 |
| Arduino Uno R3 | W5500 | Arduino.org Ethernet2 | 195.32 | 329.60 |
| Arduino Uno R3 | W5200 | WIZ820io | 191.85 | 331.27 |
| Arduino Uno R3 | W5100 | Arduino Ethernet R3 | 79.11 | 82.66 |
| Arduino Uno R3 | W5100 | Ethernet R2 (clone) | 79.27 | 82.66 |
| Arduino Leonardo | W5500 | Seeed Ethernet W5500 | 179.98 | 328.14 |
| Arduino Leonardo | W5200 | WIZ820io | 183.69 | 330.30 |
| Arduino Leonardo | W5100 | Ethernet R2 (clone) | 78.75 | 82.28 |
| Mega 2560 (clone) | W5500 | Seeed Ethernet W5500 | 179.58 | 323.36 |
| Mega 2560 (clone) | W5200 | WIZ820io | 172.73 | 325.44 |
| Mega 2560 (clone) | W5100 | Ethernet R2 (clone) | 74.31 | 77.44 |
| Arduino Zero | W5500 | Seeed Ethernet W5500 | 183.13 | 305.26 |
| Arduino Zero | W5500 | Arduino.org Ethernet2 | 181.60 | 305.28 |
| Arduino Zero | W5200 | WIZ820io | 177.53 | 298.53 |
| Arduino Zero | W5100 | Arduino Ethernet R3 | 91.33 | 96.64 |
| Arduino Zero | W5100 | Ethernet R2 (clone) | 91.42 | 96.64 |
| Arduino MKR1000 | W5500 | MKR ETH | 181.27 | 298.93 |
| Arduino MKR1000 | W5200 | WIZ820io | 125.20 | 291.98 |
| Arduino Uno Wifi Rev2 | W5500 | Seeed Ethernet W5500 | 163.86 | 213.36 |
| Arduino Uno Wifi Rev2 | W5500 | Arduino.org Ethernet2 | 169.72 | 212.88 |
| Arduino Uno Wifi Rev2 | W5200 | WIZ820io | 161.94 | 212.19 |
| Arduino Uno Wifi Rev2 | W5100 | Arduino.org Ethernet2 | 69.50 | 72.23 |
| Arduino Uno Wifi Rev2 | W5100 | Ethernet R2 (clone) | 69.55 | 72.30 |
For more information about these benchmarks: https://www.pjrc.com/arduino-ethernet-library-2-0-0/
ESP32 may require edit to SPI.h to add SPI.transfer(data, size) espressif/arduino-esp32#1623