Disclosed are systems, methods and computer program products for performing antivirus analysis of a file. Particularly, antivirus software detects an attempt to execute a file on a computer and collects information about current file attributes. The software retrieves information about old file attributes. The software then compares current file attributes with the old file attributes to determine whether the file has been modified. When the file is determined to be modified, the software synchronously accesses the file to perform antivirus analysis thereof. During the synchronous access of the file, one or more other programs are prohibited from accessing the analyzed file. When the file is determined to be unmodified, the software asynchronously accesses the file. During the asynchronous access of the file one or more of the other programs are allowed to access the analyzed file.