# UNDF: UNDF-2026-000001161
# UNDF: (to be assigned)
--- a/src/export.cpp
+++ b/src/export.cpp
@@ -1220,24 +1220,23 @@ void ExportWrlMeshes(FILE *f, const char *basename, SMesh *sm, RgbaColor clr) {
         fputs("        ]\n"
               "        color Color { color [\n", f);
         // Output triangle colors.
         std::vector<int> triangle_colour_ids;
-        std::vector<RgbaColor> colours_present;
+        // Use unordered_map<packed-RGBA, index> for O(1) colour dedup
+        // instead of std::vector + std::find_if which is O(T*C).
+        // RgbaColor::ToPackedInt() produces a unique uint32_t per RGBA tuple.
+        std::unordered_map<uint32_t, int> colour_to_index;
+        int next_colour_index = 0;
         for(const auto & sp : op.second) {
             for(const auto & tr : sp) {
-                const auto colour_itr = std::find_if(colours_present.begin(), colours_present.end(),
-                                                     [&](const RgbaColor & c) {
-                                                         return c.Equals(tr.meta.color);
-                                                     });
-                if(colour_itr == colours_present.end()) {
+                uint32_t key = tr.meta.color.ToPackedInt();
+                auto it = colour_to_index.find(key);
+                if(it == colour_to_index.end()) {
                     fprintf(f, "          %.10f %.10f %.10f,\n",
                             tr.meta.color.redF(),
                             tr.meta.color.greenF(),
                             tr.meta.color.blueF());
-                    triangle_colour_ids.push_back(colours_present.size());
-                    colours_present.insert(colours_present.end(), tr.meta.color);
+                    colour_to_index[key] = next_colour_index;
+                    triangle_colour_ids.push_back(next_colour_index);
+                    ++next_colour_index;
                 } else {
-                    triangle_colour_ids.push_back(colour_itr - colours_present.begin());
+                    triangle_colour_ids.push_back(it->second);
                 }
             }
         }