diff --git a/gpx/src/gpx.ts b/gpx/src/gpx.ts
index 90a2cb5b..6884ab82 100644
--- a/gpx/src/gpx.ts
+++ b/gpx/src/gpx.ts
@@ -412,10 +412,10 @@ export class TrackSegment extends GPXTreeLeaf {
     // Producers
     replace(segment: number, start: number, end: number, points: TrackPoint[]) {
         return produce(this, (draft) => {
-            let og = getOriginal(draft);
+            let og = getOriginal(draft); // Read as much as possible from the original object because it is faster
             let trkpt = og.trkpt.slice();
             trkpt.splice(start, end - start + 1, ...points);
-            draft.trkpt = freeze(trkpt);
+            draft.trkpt = freeze(trkpt); // Pre-freeze the array, faster as well
         });
     }
 
diff --git a/website/src/lib/components/toolbar/tools/routing/RoutingControls.ts b/website/src/lib/components/toolbar/tools/routing/RoutingControls.ts
index 527f8914..6f068778 100644
--- a/website/src/lib/components/toolbar/tools/routing/RoutingControls.ts
+++ b/website/src/lib/components/toolbar/tools/routing/RoutingControls.ts
@@ -432,17 +432,18 @@ export class RoutingControls {
             return false;
         }
 
-        let start = anchors[0].point._data.index + 1;
-        let end = anchors[anchors.length - 1].point._data.index - 1;
-
         if (anchors[0].point._data.index === 0) { // First anchor is the first point of the segment
-            anchors[0].point = response[0]; // Update the first anchor in case it was not on a road
-            start--; // Remove the original first point
+            anchors[0].point = response[0]; // Update the first anchor
+            anchors[0].point._data.index = 0;
+        } else {
+            response.splice(0, 0, anchors[0].point); // Keep the original start point
         }
 
         if (anchors[anchors.length - 1].point._data.index === segment.trkpt.length - 1) { // Last anchor is the last point of the segment
-            anchors[anchors.length - 1].point = response[response.length - 1]; // Update the last anchor in case it was not on a road
-            end++; // Remove the original last point
+            anchors[anchors.length - 1].point = response[response.length - 1]; // Update the last anchor
+            anchors[anchors.length - 1].point._data.index = segment.trkpt.length - 1;
+        } else {
+            response.push(anchors[anchors.length - 1].point); // Keep the original end point
         }
 
         for (let i = 1; i < anchors.length - 1; i++) {
@@ -465,7 +466,7 @@ export class RoutingControls {
             anchor.point._data.zoom = 0; // Make these anchors permanent
         });
 
-        dbUtils.applyToFile(this.fileId, (file) => file.replace(anchors[0].segmentIndex, start, end, response));
+        dbUtils.applyToFile(this.fileId, (file) => file.replace(anchors[0].segmentIndex, anchors[0].point._data.index, anchors[anchors.length - 1].point._data.index, response));
 
         return true;
     }
diff --git a/website/src/lib/components/toolbar/tools/routing/Simplify.ts b/website/src/lib/components/toolbar/tools/routing/Simplify.ts
index 54c13655..5e856100 100644
--- a/website/src/lib/components/toolbar/tools/routing/Simplify.ts
+++ b/website/src/lib/components/toolbar/tools/routing/Simplify.ts
@@ -26,7 +26,7 @@ export function computeAnchorPoints(segment: TrackSegment) {
     segment._data.anchors = true;
 }
 
-export function ramerDouglasPeucker(points: TrackPoint[], epsilon: number = 50, start: number = 0, end: number = points.length - 1): SimplifiedTrackPoint[] {
+export function ramerDouglasPeucker(points: readonly TrackPoint[], epsilon: number = 50, start: number = 0, end: number = points.length - 1): SimplifiedTrackPoint[] {
     if (points.length == 0) {
         return [];
     } else if (points.length == 1) {
@@ -45,7 +45,7 @@ export function ramerDouglasPeucker(points: TrackPoint[], epsilon: number = 50,
     return simplified;
 }
 
-function ramerDouglasPeuckerRecursive(points: TrackPoint[], epsilon: number, start: number, end: number, simplified: SimplifiedTrackPoint[]) {
+function ramerDouglasPeuckerRecursive(points: readonly TrackPoint[], epsilon: number, start: number, end: number, simplified: SimplifiedTrackPoint[]) {
     let largest = {
         index: 0,
         distance: 0
diff --git a/website/src/lib/db.ts b/website/src/lib/db.ts
index 346f2f5d..cb094f8d 100644
--- a/website/src/lib/db.ts
+++ b/website/src/lib/db.ts
@@ -1,6 +1,6 @@
 import Dexie, { liveQuery } from 'dexie';
 import { GPXFile, GPXStatistics } from 'gpx';
-import { enableMapSet, enablePatches, produceWithPatches, applyPatches, type Patch, type WritableDraft, castDraft } from 'immer';
+import { enableMapSet, enablePatches, applyPatches, type Patch, type WritableDraft, castDraft, Immer } from 'immer';
 import { writable, get, derived, type Readable, type Writable } from 'svelte/store';
 import { fileOrder, initTargetMapBounds, selectedFiles, updateTargetMapBounds } from './stores';
 import { mode } from 'mode-watcher';
@@ -9,6 +9,8 @@ import { defaultBasemap, defaultBasemapTree, defaultOverlayTree, defaultOverlays
 enableMapSet();
 enablePatches();
 
+const noFreezeImmer = new Immer({ autoFreeze: false }); // Do not freeze files that are not concerned by an update, otherwise cannot assign anchors for them
+
 class Database extends Dexie {
 
     fileids!: Dexie.Table<string, string>;
@@ -210,7 +212,7 @@ export const canRedo: Readable<boolean> = derived([patchIndex, patchMinMaxIndex]
 
 // Helper function to apply a callback to the global file state
 function applyGlobal(callback: (files: Map<string, GPXFile>) => void) {
-    const [newFileState, patch, inversePatch] = produceWithPatches(fileState, callback);
+    const [newFileState, patch, inversePatch] = noFreezeImmer.produceWithPatches(fileState, callback);
 
     storePatches(patch, inversePatch);
 
@@ -219,7 +221,7 @@ function applyGlobal(callback: (files: Map<string, GPXFile>) => void) {
 
 // Helper function to apply a callback to multiple files
 function applyToFiles(fileIds: string[], callback: (file: WritableDraft<GPXFile>) => GPXFile) {
-    const [newFileState, patch, inversePatch] = produceWithPatches(fileState, (draft) => {
+    const [newFileState, patch, inversePatch] = noFreezeImmer.produceWithPatches(fileState, (draft) => {
         fileIds.forEach((fileId) => {
             let file = draft.get(fileId);
             if (file) {