try this
To each Audio Instrument track insert an I/O plug-in. (Stereo>Logic>Helper>I/O).
When the I/O Plug-in pops up on the screen, assign any bus to its output (1-2, for instance) and assign another bus to its input (1-2, for instance). Then put the plug-in into BYPASS mode. This forces Logic to treat this channel as a live input, thereby eliminating any latency that would otherwise occur.
from the old EXS 24 / VSL as slave instructions
To each Audio Instrument track insert an I/O plug-in. (Stereo>Logic>Helper>I/O).
When the I/O Plug-in pops up on the screen, assign any bus to its output (1-2, for instance) and assign another bus to its input (1-2, for instance). Then put the plug-in into BYPASS mode. This forces Logic to treat this channel as a live input, thereby eliminating any latency that would otherwise occur.
from the old EXS 24 / VSL as slave instructions