Why SD upload is so slow ? How to increase speed ?

[luc-github]

Why SD upload is so slow ?
This is due to upload protocol itself using M28/M29 gcode commands, this protocol actually send command by command, verifying command is correct before writing it to SD, this speed is even slower when checksum is used (adding more calculation and time) and when GCODE is converted from text to binary. So increase baud rate will increase transfert a little but not making the upload 'fast'

This is not related to ESP3D. But to the fact that the protocol is not a file protocol but a command protocol
How to increase speed ?
As explained above ESP3D is not the root cause and may not be the solution

• Use WiFi SD card, they are super fast for upload , but use proper one most of them allow only download not upload - I use the Toshiba flash air with this https://github.com/luc-github/Flashair-FM
• Use a board which share the SD card between ESP and Main board like azteeg wifi : http://www.panucatt.com/azteeg_X5_mini_reprap_3d_printer_controller_p/ax5mini.htm
  or WiFi back pack : https://www.panucatt.com/ProductDetails.asp?ProductCode=WB8266
  ESP3D 3.0 with ESP32 with SD card reader will act as host, so upload will be faster but file won't be on SD printer card, only on ESP SD card so no SD Print but host like printing, which mean print will be launch from Web browser or from supported touch screen (under development)

Note: MKS fast upload protocol is implemented but it works only with Mks Boards

[luc-github]

there is an affordable solution now for SD WiFi : https://github.com/FYSETC/SD-WIFI-PRO