8x8x8 multiplexed LED cube with an Arduino Mega 2560

Try this: use the TPIC6B595 OE to disable the outputs when switching.

Use direct port manipulation to make it go faster.
So that OE is bit 2 and SS/Latch is bit 3, both on port D:

PORTD = PORTD | B00000010; // bring OE/ high
// xfer data
    SPI.transfer (B00000000);
    SPI.transfer (B00000001); //leftmost, frontmost corner cathode column
    SPI.transfer (B00000001); //bottom anode plane
PORTD = PORTD & B11111011; // bring SS/latch low
PORTD = PORDT | B00000110;  //  bring OE/ an SS/latch high