For most users, the safest path is to either install the original Windows 8.1 ISO and slim it down yourself (using tools like NTLite) or make the leap to a lightweight Linux distribution. Both options provide more transparency, better security, and—in the case of Linux—continued software updates.
The standard Windows 8.1 installation is relatively efficient by today's standards, but it still contains bloatware, background telemetry services, visual effects, and Metro apps that consume precious resources on low-end machines. The "Lite" philosophy is a radical one—removing every non-essential component to leave behind only the core operating system. Windows 8.1 Lite Archive.org