In this article, we describe the performance evaluation of INACT tool which is developed for cataloguing of high-level and low-level metadata of the evidence material. INACT tool can be used by police forces in the cases of prosecution of such crimes as as possession and distribution of child pornography (CP). In live forensic cases, the time to first hit (time when the first image containing e.g. CP is found) is important, as then further legal actions are justified (such as arrest of the suspect and his hardware). The performance evaluation of first hit was performed on real data with the cooperation of Czech Police, Department of Internet Crime.