It will largely depend on various factors, which are: how many frequency points you take within this wide frequency range, what ADC filters' settings you use, and what's the number of DFT points you take.
The equation to get the time per input frequency point, for a certain ADC sampling rate (defaults is 800kHz), ADC filters' settings, and DFT points, is: Time = DFT_Points/(ADC_Rate/Sinc_Filters_OSR).
You could change DFT number of points & Sinc filters (Sinc2 & Sinc3) settings to have more or less time, depending on the frequency of operation & required number of cycles to be processed.
