I'm using a B-U585I-IOT02A discovery kit that that has the STM32U5 MCU. I'm looking to evaluate if the STM32U5 MCU can run an FFT in real time and how to evaluate the performace of the STM32U5 MCU running FFT's. Are there any tools to help me do that or what the best way to accomplish this?
It has a Cortex-M33
You should be able to use the CMSIS DSP libraries to process an FFT
You can use the DWT's CYCCNT to time execution in processor clocks.
Find some code and data you want to benchmark.