A method for reducing the size of the AV database on a user computer by dynamically generating an AV database according to user parameters is provided. Critical user parameters that affect the content of the AV database required for this user are determined. The AV database for the single user is generated based on the user parameters. When the parameters of the user computer change or when new malware threats are detected, the user AV database is dynamically updated according to the new parameters and the new malware threats. The update procedure becomes more efficient since a need of updating large volumes of data is eliminated. The AV system, working with a small AV database, finds malware objects more efficiently and uses less of computer system resources.