diff --git a/lib/galaxy/webapps/base/api.py b/lib/galaxy/webapps/base/api.py
index 01127f21fbb..a31d3e76336 100644
--- a/lib/galaxy/webapps/base/api.py
+++ b/lib/galaxy/webapps/base/api.py
@@ -40,6 +40,7 @@ from galaxy.web.framework.base import walk_controller_modules
 
 if TYPE_CHECKING:
     from starlette.background import BackgroundTask
+    from starlette.routing import BaseRoute
     from starlette.types import (
         Receive,
         Scope,
@@ -251,6 +252,21 @@ def add_request_id_middleware(app: FastAPI):
     app.add_middleware(RawContextMiddleware, plugins=(RequestIdPlugin(force_new_uuid=True),))
 
 
+def build_route_name_index(app: FastAPI) -> dict[str, list["BaseRoute"]]:
+    """Build a name -> [route] index for O(1) route lookup.
+
+    Routes are immutable after app startup, so this index is built once
+    and reused for all subsequent requests. For most route names there
+    is exactly one candidate, making lookups O(1) instead of O(n).
+    """
+    index: dict[str, list[BaseRoute]] = {}
+    for route in app.routes:
+        name = getattr(route, "name", None)
+        if name:
+            index.setdefault(name, []).append(route)
+    return index
+
+
 def include_all_package_routers(app: FastAPI, package_name: str):
     responses: dict[Union[int, str], dict[str, Any]] = {
         "4XX": {
diff --git a/lib/galaxy/webapps/galaxy/api/__init__.py b/lib/galaxy/webapps/galaxy/api/__init__.py
index c8dd2645775..d95e8939f87 100644
--- a/lib/galaxy/webapps/galaxy/api/__init__.py
+++ b/lib/galaxy/webapps/galaxy/api/__init__.py
@@ -223,7 +223,7 @@ class UrlBuilder:
                 else:
                     url = str(self.request.url_for(name, **path_params))
             else:
-                url = self.request.app.url_path_for(name, **path_params)
+                url = self._url_path_for(name, **path_params)
             if query_params:
                 url = f"{url}?{urlencode(query_params)}"
             return url
@@ -233,6 +233,24 @@ class UrlBuilder:
                 path_params.update(query_params)
             return web.url_for(name, **path_params)
 
+    def _url_path_for(self, name: str, **path_params) -> str:
+        """O(1) route lookup using the app's pre-built name index.
+
+        The index is built once at startup in initialize_fast_app and maps
+        route names to their route objects, replacing Starlette's O(n)
+        linear scan with a direct dict lookup.
+        """
+        candidates = self.request.app.state.route_name_index.get(name)
+        if candidates is not None:
+            for route in candidates:
+                try:
+                    return route.url_path_for(name, **path_params)
+                except NoMatchFound:
+                    pass
+            raise NoMatchFound(name, path_params)
+        # Fallback for names not in the index (e.g. Mount sub-routes)
+        return self.request.app.url_path_for(name, **path_params)
+
 
 class GalaxyASGIRequest(GalaxyAbstractRequest):
     """Wrapper around Starlette/FastAPI Request object.
diff --git a/lib/galaxy/webapps/galaxy/fast_app.py b/lib/galaxy/webapps/galaxy/fast_app.py
index 2f05d8c86df..43e4dd8d4a5 100644
--- a/lib/galaxy/webapps/galaxy/fast_app.py
+++ b/lib/galaxy/webapps/galaxy/fast_app.py
@@ -24,6 +24,7 @@ from galaxy.webapps.base.api import (
     add_exception_handler,
     add_raw_context_middlewares,
     add_request_id_middleware,
+    build_route_name_index,
     GalaxyFileResponse,
     include_all_package_routers,
 )
@@ -214,6 +215,7 @@ def initialize_fast_app(gx_wsgi_webapp, gx_app):
     wsgi_handler = WSGIMiddleware(gx_wsgi_webapp)
     gx_app.haltables.append(("WSGI Middleware threadpool", wsgi_handler.executor.shutdown))
     include_tus(app, gx_app)
+    app.state.route_name_index = build_route_name_index(app)
     app.mount("/", wsgi_handler)  # type: ignore[arg-type]
     if gx_app.config.galaxy_url_prefix != "/":
         parent_app = FastAPI()