A several-thousand-waypoint park4night area export re-parses the whole file with REXML on every toggle — ~2.4s for a 5k-waypoint/3.6MB sample, so tens of seconds for a 50k-waypoint one, likely the actual cause behind a "Could not load" report on a 41.5MB export. MapLibre already clusters the waypoint layer client-side, so the bottleneck was never rendering — cache the GeoJSON conversion alongside the source file (invalidated by mtime) instead of a bigger bbox/tiling rework.