Antimalware Core Service is one of the components of the Microsoft Defender security software designed to ensure security on Windows. This service differs from Antimalware Service Executable, which operates as MsMpEng.exe. The activities of the above-mentioned components work in the background to detect any possible threats to your computer. The load from their activities can be increased by downloading files, installing applications, or launching a scan. In case of increased usage of computer resources, check Task Manager and Windows Security to see whether the scan is running at the moment. Update your security if needed.