UART DMA

ADSP-BF533 has dedicated DMA for each transmitter of receiver of UART. You can reduce the load of processor by using DMA. When you use the UART DMA, you should be careful to set the ETBEI and ERBFI of UART_IER to 1 for TX DMA and RX DMA, respectively. This is not intuitive, but you should do it. To avoid the spurious interrupt, You should enable DMA before turning ETBEI or ERBFI to 1.
Or if you are not so critical to the performance, you may be able to handle UART without DMA. The interrupt overhead of 115200bps is less than 1%.