Figma is built in Web-Assembly (compiled from C++) [1] and Canvas, basically sidestepping the vast majority of the web stack. That's why it's fast.
[1]: https://www.figma.com/blog/webassembly-cut-figmas-load-time-...
[1]: https://www.figma.com/blog/webassembly-cut-figmas-load-time-...
It turns out HN is prone to the same sort of knee jerk reactions as most every other "social news" site (even if to a lesser degree). Who would've thought?!