Microsoft will be enabling VBS on most new PS's and that can slow games down by up to 25%.
So what is VBS?
Virtualization-Based Security (VBS), a setting introduced into Windows 10 which uses hardware and software virtualisation to enhance the security of your system. It basically creates an isolated subsystem that helps prevent malware from screwing your PC. Sounds good, but it has been shown to slow the frame rate of some games down by 28%.
Microsoft explains it as follows: "VBS uses hardware virtualization features to create and isolate a secure region of memory from the normal operating system. Windows can use this 'virtual secure mode' to host a number of security solutions, providing them with greatly increased protection from vulnerabilities in the operating system, and preventing the use of malicious exploits which attempt to defeat protections."