diff --git a/src/engine/Context.d b/src/engine/Context.d
index 52b5875..f2ea635 100644
--- a/src/engine/Context.d
+++ b/src/engine/Context.d
@@ -5,10 +5,22 @@ import std.string;
 import sdl;
 import engine;
 
+enum initFps = 60.;
+
 struct Context {
   bool running = true;
-  MonoTime updated;
-  Duration elapsed;
+
+  package {
+    // [ms]
+    ulong dur = cast(ulong)(1000 / initFps);
+    ulong updated;
+    ulong elapsed;
+  }
+  real fps() => 1000. / dur;
+  real fps(real v) {
+    dur = cast(ulong)(1000 / v);
+    return fps;
+  }
 
   GameObject root;
   InputManager im;
diff --git a/src/engine/GameObject.d b/src/engine/GameObject.d
index 5df0f9b..999c43b 100644
--- a/src/engine/GameObject.d
+++ b/src/engine/GameObject.d
@@ -19,7 +19,7 @@ class GameObject: Loggable {
 
   package Context* ctx;
 
-  auto dur() const => real(ctx.elapsed.total!"usecs") / 4096;
+  real dur() const => ctx.elapsed / 10.;
   auto im() const => ctx.im;
   auto everyone() => ctx.root.descendant;
 
diff --git a/src/engine/System.d b/src/engine/System.d
index 8e771b7..2a9e811 100644
--- a/src/engine/System.d
+++ b/src/engine/System.d
@@ -29,13 +29,18 @@ class System: Loggable {
   }
 
   void run() {
+    ctx.updated = SDL_GetTicks64;
     ctx.root.realSetup(&ctx);
-    ctx.updated = MonoTime.currTime;
 
     loop; // 初回レンダリング
     while(ctx.running) {
-      auto cur = MonoTime.currTime;
+      auto cur = SDL_GetTicks64;
       auto elapsed = cur - ctx.updated;
+      if(elapsed < ctx.dur) {
+        import core.thread.osthread;
+        Thread.sleep(800.usecs);
+        continue;
+      }
       ctx.updated = cur;
       ctx.elapsed = elapsed;
 
@@ -44,44 +49,45 @@ class System: Loggable {
   }
 
   void loop() {
-    SDL_Event e;
-    SDL_PollEvent(&e);
-
-    auto keyUpdate = false;
-    switch(e.type) {
-      case SDL_KEYDOWN:
-        auto key = cast(char)e.key.keysym.sym;
-        auto state = ctx.im.state;
-        auto once = ctx.im.once;
-
-        if(!state[key]) once[key] = true;
-        else once[key] = false;
-
-        state[key] = true;
-        keyUpdate = true;
-        break;
-
-      case SDL_KEYUP:
-        ctx.im.state[cast(char)e.key.keysym.sym] = false;
-        break;
+    auto keyUpdated = false;
 
-      case SDL_MOUSEMOTION:
-        auto motion = e.motion;
-        break;
-
-      case SDL_MOUSEBUTTONDOWN:
-      case SDL_MOUSEBUTTONUP:
-        auto btn = e.button;
-        break;
-
-      case SDL_QUIT:
-        ctx.running = false;
-        break;
-
-      default:
+    SDL_Event e;
+    while(SDL_PollEvent(&e)) {
+      switch(e.type) {
+        case SDL_KEYDOWN:
+          auto key = cast(char)e.key.keysym.sym;
+          auto state = ctx.im.state;
+          auto once = ctx.im.once;
+
+          if(!state[key]) once[key] = true;
+          else once[key] = false;
+
+          state[key] = true;
+          keyUpdated = true;
+          break;
+
+        case SDL_KEYUP:
+          ctx.im.state[cast(char)e.key.keysym.sym] = false;
+          break;
+
+        case SDL_MOUSEMOTION:
+          auto motion = e.motion;
+          break;
+
+        case SDL_MOUSEBUTTONDOWN:
+        case SDL_MOUSEBUTTONUP:
+          auto btn = e.button;
+          break;
+
+        case SDL_QUIT:
+          ctx.running = false;
+          break;
+
+        default:
+      }
     }
 
-    if(!keyUpdate)ctx.im.once ^= ctx.im.once;
+    if(!keyUpdated)ctx.im.once ^= ctx.im.once;
 
     // Collider
     auto gos = ctx.root.everyone.filter!(e => e.has!BoxCollider && e.has!Transform).array;