The ALICE Silicon Pixel Detector (SPD) forms the two innermost layers of the ALICE Inner Tracking System (ITS). It consists of two-layer barrel of hybrid silicon pixel detectors. The SPD contains 1200 pixel readout chips and about 10 7 pixel cells. The unique feature of the SPD among the vertex detectors of LHC experiments is the prompt trigger capability, called Fast-Or, which allows it to contribute to the experimental first level trigger decision. The SPD data stream includes 1200 digital signals (Fast-Or) promptly asserted by each readout chip on the presence of at least one pixel hit in the matrix. The off-detector Pixel Trigger system elaborates in real time the 1200 Fast-Or signals continuously received from the detector in order to generate a pre-processed signal for the ALICE first level trigger. All the Fast-Or signals are written in the data and available for offline analysis. In this contribution it is presented the methodology used to evaluate the performance of the Fast-Or. The methods are entirely based on offline data analysis. Results are given for a sample of data of proton–proton collisions at s = 7 TeV .