Windows XP didn't have a compositing window manager and instead sent WM_PAINT messages to apps to repaint themselves when they became visible again. That's ~30MB per window extra RAM/VRAM required for Vista and newer. So let's say ~512MB extra with 15 windows. Next, with Windows 10, Microsoft stopped optimizing their disk access for HDDs and that made it almost unusable on HDD with the same amount of RAM as 7. Next, Microsoft stopped developing their Trident/Edge web browser engine and switched to Chromium that uses a lot of RAM to store all the JIT-ted versions of JS loaded. Then came all the Electron apps that don't share the same chromium engine but instead each has it's own copy in the RAM. Then came React/React Native and it's duplicate copy of DOM that makes it faster at the expense of RAM.