GIGA USB Read speed is very slow! Something like 4 times slower than SDFat on SD drives.

[KurtE]

As an example, I have a sketch that displays images that are read from either an external SD drive that is connected
using SPI. Or from a drive plugged into the USB Host port.

When it is running off of the USB port is very obvious how much slower it is running on the USB drive versus SD card.
This sketch is up at: https://github.com/KurtE/Arduino_GIGA-stuff/tree/main/sketches/tft_picture_view_sd_giga_shield_24Bit

But I am sure it is true on most any other program as well...

With this sketch I show in the debug window how long it takes to read and display each image.

An example of a larger image file, when read from SD Card:

Loading image 'Sharon Barn.bmp'
Image size: 1716x1312 depth:24Scale: 1/3 Image Offsets (114, 21)
!!File:Sharon Barn.bmp Time:6961 writeRect calls:0

And when read from USB:

Loading image '/usb/Sharon Barn.bmp'
Image size: 1716x1312 depth:24Scale: 1/3 Image Offsets (114, 21)
!!File:/usb/Sharon Barn.bmp Time:29426 writeRect calls:0

So the same image time went from about 7 seconds to almost 30 seconds to display.