The option 'Direct display' speeds up DSP processing, but the displays are less clean (waves on the screen) and redraws are impossible. This option is not available in 256 colours or monochrome. In Falcon True Color and direct display mode, the DSP works in background mode for transfers (it interrupts the 680x0), which allows decompression of an image while the next image is being loaded.
If the option 'Good quality' is NOT checked, decompression without the DSP will be faster at the cost of colour quality; this applies to iv31/32 (Intel Indeo) compression among others. In Falcon True Color mode or 32768/65536 colours, the quality is slightly worse on CVID compression (Cinepak). In 256 colours, dithering is disabled for movies in 32768 and 16 million colours (this makes it faster without the DSP, but there is a substantial loss of quality).