Given that these frequent alerts started after installing a dubious 'performance optimization' program, it is likely that the program is scareware or rogue security software which is known to display false alerts to trick the user into purchasing unnecessary or malicious software. The first step should be to uninstall this questionable program using the system's add or remove programs feature; doing so could likely stop the false alerts. Running an authoritative antivirus scan is the next logical step after removing the potentially harmful program but is not the first action. Updating antivirus definitions is essential in general but does not address the immediate issue of the suspected rogue program, which should be removed first. Purchasing the premium software promoted by the alerts would only worsen the situation as it is indicative of a scam.