If your PC struggles with official Windows 8.1, consider:

A "Lite" build of Windows 8.1 can often run with initial RAM usage as low as 400–430 MB

created by third parties to reduce system resource footprints. Resource Usage: These versions typically idle at roughly 400MB–800MB of RAM and use less than 6GB of disk space Modifications:

The "Lite" version mentioned in your query typically refers to unofficial, modified ISOs created by third parties to reduce system resource usage by removing non-essential components. Key Features of Build 9374 Kiosk Mode: