diff --git a/backend/src/main/resources/db/migration/V62__index_fk_columns.sql b/backend/src/main/resources/db/migration/V62__index_fk_columns.sql
new file mode 100644
index 00000000..4cbb254c
--- /dev/null
+++ b/backend/src/main/resources/db/migration/V62__index_fk_columns.sql
@@ -0,0 +1,8 @@
+-- Speeds up "documents by sender" queries used on /persons/[id] Korrespondenz-Überblick (#306),
+-- /briefwechsel, and bulk-edit flows.
+CREATE INDEX IF NOT EXISTS idx_documents_sender_id
+    ON documents(sender_id);
+
+-- Speeds up "comments by author" queries on admin user detail and (future) contributor profile.
+CREATE INDEX IF NOT EXISTS idx_comments_author_id
+    ON document_comments(author_id);
diff --git a/backend/src/test/java/org/raddatz/familienarchiv/MigrationIntegrationTest.java b/backend/src/test/java/org/raddatz/familienarchiv/MigrationIntegrationTest.java
index a01682ab..425d0f59 100644
--- a/backend/src/test/java/org/raddatz/familienarchiv/MigrationIntegrationTest.java
+++ b/backend/src/test/java/org/raddatz/familienarchiv/MigrationIntegrationTest.java
@@ -399,6 +399,24 @@ class MigrationIntegrationTest {
               AND dc.annotation_id IS NOT NULL
             """;
 
+    // ─── V62: indexes on FK columns ──────────────────────────────────────────
+
+    @Test
+    void v62_idx_documents_sender_id_exists() {
+        Integer count = jdbc.queryForObject(
+                "SELECT COUNT(*) FROM pg_catalog.pg_indexes WHERE tablename = 'documents' AND indexname = 'idx_documents_sender_id'",
+                Integer.class);
+        assertThat(count).isEqualTo(1);
+    }
+
+    @Test
+    void v62_idx_comments_author_id_exists() {
+        Integer count = jdbc.queryForObject(
+                "SELECT COUNT(*) FROM pg_catalog.pg_indexes WHERE tablename = 'document_comments' AND indexname = 'idx_comments_author_id'",
+                Integer.class);
+        assertThat(count).isEqualTo(1);
+    }
+
     // ─── V63+V64: group_permissions dedup + primary key ──────────────────────
 
     @Test