In SDK's plash example as part of internal flash manipulation routines, you also ivalidate L1 and FtFx caches :
/* Post-preparation work about flash Cache/Prefetch/Speculation. */
is this are mandatory operations if caches is NOT going to be initialised at all.
Those flash routines going to be used in custom bootloader what flash new firmware to some space
and jump to it.
Any extra performance is no need and for simplify bootloader is possible to disable OR no init any code cache
at all ?
Or those code cache operations must to be activated and used as in example ?