Some of the IQmath functions use look-up tables. Many of these tables are included in the boot ROM of 28x devices. Using the boot ROM copy will save you memory space and the time required to load the tables themselves. Note that the boot ROM on some devices is 1 wait state compared to SARAM that is usually 0 wait state. The look-up tables are usually not accessed often enough for this to cause an issue with performance. Therefore, in most cases you will want to use the boot ROM look-up tables.