diff --git a/app/Http/Controllers/Staff/StudiesController.php b/app/Http/Controllers/Staff/StudiesController.php
index 54a594e..0f960ca 100644
--- a/app/Http/Controllers/Staff/StudiesController.php
+++ b/app/Http/Controllers/Staff/StudiesController.php
@@ -12,7 +12,6 @@ class StudiesController extends HashidControllerBase
     public function index()
     {
         $studies = UserStudyListerFactory::getLister()->all();
-        dd($studies);
 
         return view('staff.studies.index', compact('studies'));
     }
diff --git a/app/Models/Study.php b/app/Models/Study.php
index c3c71d9..5b322b8 100644
--- a/app/Models/Study.php
+++ b/app/Models/Study.php
@@ -66,11 +66,11 @@ public function getHistoryLink(): string
     {
         $user = auth()->user();
         if ($user->may(Permission::StudyHistoryEdit)) {
-            return route('staff.history.edit', _h($this->id));
+            return route('staff.history.edit', $this->hash);
         }
 
         if ($user->may(Permission::StudyHistoryView)) {
-            return route('staff.history.view', _h($this->id));
+            return route('staff.history.view', $this->hash);
         }
 
         return '#';
diff --git a/app/Models/StudyDetails.php b/app/Models/StudyDetails.php
index 83e4ccc..486ff08 100644
--- a/app/Models/StudyDetails.php
+++ b/app/Models/StudyDetails.php
@@ -2,12 +2,15 @@
 
 namespace App\Models;
 
+use App\Models\Traits\HashableId;
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
 
 class StudyDetails extends BaseModel
 {
     protected $table = 'study_details';
 
+    use HashableId;
+
     public function study(): BelongsTo
     {
         return $this->belongsTo(Study::class);
diff --git a/app/Models/User.php b/app/Models/User.php
index f8808d4..6906cea 100644
--- a/app/Models/User.php
+++ b/app/Models/User.php
@@ -5,6 +5,7 @@
 // use Illuminate\Contracts\Auth\MustVerifyEmail;
 use App\Models\Enums\Permission;
 use App\Models\Enums\UserRole;
+use App\Models\Traits\HashableId;
 use Database\Factories\UserFactory;
 use Illuminate\Database\Eloquent\Factories\HasFactory;
 use Illuminate\Foundation\Auth\User as Authenticatable;
@@ -21,6 +22,7 @@ class User extends Authenticatable
     /** @use HasFactory<UserFactory> */
     use HasFactory;
 
+    use HashableId;
     use HasProfilePhoto;
     use HasRoles;
     use Notifiable;
@@ -90,11 +92,14 @@ public function scopeActive($query)
 
     public function isAdmin(): bool
     {
-        return $this->hasRole(UserRole::Admin);
+        return cache()->remember('user.is_admin:'.$this->id,
+            5 * 60,
+            fn () => $this->hasRole(UserRole::Admin)
+        );
     }
 
-    public function may(Permission $perm): bool
+    public function may(Permission|iterable|string $perm): bool
     {
-        return $this->hasRole(UserRole::Admin) || $this->can($perm);
+        return $this->isAdmin() || $this->can($perm);
     }
 }
diff --git a/app/helpers.php b/app/helpers.php
index 8a2d971..a366c9b 100644
--- a/app/helpers.php
+++ b/app/helpers.php
@@ -47,3 +47,14 @@ function user_per_page(?int $user_id = null): int
         return settings()->get("user.{$user_id}.pagination.per_page", config('app.pagination.per_page'));
     }
 }
+
+if (! function_exists('may')) {
+    function may(BackedEnum|iterable|string $perm): bool
+    {
+        if (auth()->user()->isAdmin()) {
+            return true;
+        }
+
+        return auth()->user()->can($perm);
+    }
+}