ZBrush uses its own virtual memory file, located within the ZBrush directory itself. So it completely ignores the Windows virtual memory.
You should put ZBrush on the fastest drive you have in your machine.
Now for overall operating system performance you’re usually best off putting the Windows swap file on a different drive from the OS. This will improve Windows’ performance a bit and it will also free up disk space on your system drive. That can indirectly benefit ZBrush even though it won’t directly improve performance.