Hi @bitbank,
There have been some updates to the Linux kernel and the UEFI boot firmware which may improve the performance of SPI. You can test your setup using the latest T7 image with the latest firmware.
Note that you may also need to set the required SPI bus to operate in GPI DMA mode by setting the option Radxa Platform Configuration -> GPIO -> QUPV3_xxx Mode to SPI in UEFI BIOS.
