Hi,
we have no such sample code because this is not a common question or requirement.
What plays the biggest role is system frequency. Peripherals adds some current consumption too, of course, but it is not so significant as increasing of the system clock. So, most important point is to configure highest possible system clock.
You can reuse some codes from this example:
https://community.nxp.com/docs/DOC-102744
or from other examples:
https://community.nxp.com/docs/DOC-329623#MPC5674F
And generally, just turn on all peripherals. You can let the DMA to transfer large blocks of data, you can erase some large flash block and so on…
Regards,
Lukas