Interesting approach. Recently (in SwiftUI) I did something similar using Ramer–Douglas–Peucker to retain only significant points. Not as sophisticated, but took about half a day to implement. Render lag went from annoying to barely noticeable.
I was just about to write down that it would be too difficult to de RDP simplification in the (ClickHouse) database, but then I recalled PostGIS has it built in and low and behold, there is also something in ClickHouse for this [0]. Back to the drawing board.
[0] https://clickhouse.com/codebrowser/ClickHouse/contrib/boost/...
I'm not super-familiar with the Ramer–Douglas–Peucker algorithm itself but I've used implementations of it, and, from the looks of it, its CPU cost would largely be offset by the savings in triangulation done by egui's renderer (also done on CPU currently).
Given a first and last point, it finds the point furthest away from a straight line connection, then recursively divides down the pairs of (first, furthest) and (last, furthest) only if the furthest point is above a minimum threshold distance from a straight line connection.