about 130Mbytes. ... I can easily achieve that level of capacity with RAM
How do you plan to do this?
I suppose I could move data to RAM from the SD card via SPI. I assume a sequential read would be faster...
SPI on AVR is slow since it is at not DMA and at 8 MHz max.
My guess is that a copy from SD to RAM will be at 250 KB/sec or less. 130 MB will take 8-10 minutes.