diff --git a/kitty/boss.py b/kitty/boss.py
index 17435299f..37a6948a1 100644
--- a/kitty/boss.py
+++ b/kitty/boss.py
@@ -97,7 +97,7 @@ class Boss:
         self.ui_timers = Timers()
         self.child_monitor = ChildMonitor(
             opts.repaint_delay / 1000.0, glfw_window.window_id(),
-            self.on_child_death, self.update_screen, self.ui_timers,
+            self.on_child_death, self.update_screen, self.ui_timers, self.render,
             DumpCommands(args) if args.dump_commands or args.dump_bytes else None)
         set_boss(self)
         self.current_font_size = opts.font_size
diff --git a/kitty/child-monitor.c b/kitty/child-monitor.c
index b792ce906..cbebb1147 100644
--- a/kitty/child-monitor.c
+++ b/kitty/child-monitor.c
@@ -89,12 +89,12 @@ self_pipe(int fds[2]) {
 static PyObject *
 new(PyTypeObject *type, PyObject *args, PyObject UNUSED *kwds) {
     ChildMonitor *self;
-    PyObject *dump_callback, *death_notify, *update_screen, *timers, *wid;
+    PyObject *dump_callback, *death_notify, *update_screen, *timers, *wid, *render_func;
     int ret;
     double repaint_delay;
 
     if (created) { PyErr_SetString(PyExc_RuntimeError, "Can have only a single ChildMonitor instance"); return NULL; }
-    if (!PyArg_ParseTuple(args, "dOOOOO", &repaint_delay, &wid, &death_notify, &update_screen, &timers, &dump_callback)) return NULL; 
+    if (!PyArg_ParseTuple(args, "dOOOOOO", &repaint_delay, &wid, &death_notify, &update_screen, &timers, &render_func, &dump_callback)) return NULL; 
     glfw_window_id = PyLong_AsVoidPtr(wid);
     created = true;
     if ((ret = pthread_mutex_init(&children_lock, NULL)) != 0) {
@@ -111,6 +111,7 @@ new(PyTypeObject *type, PyObject *args, PyObject UNUSED *kwds) {
     if (self == NULL) return PyErr_NoMemory();
     self->death_notify = death_notify; Py_INCREF(death_notify);
     self->update_screen = update_screen; Py_INCREF(self->update_screen);
+    self->render_func = render_func; Py_INCREF(self->render_func);
     self->timers = (Timers*)timers; Py_INCREF(timers);
     if (dump_callback != Py_None) {
         self->dump_callback = dump_callback; Py_INCREF(dump_callback);
@@ -131,6 +132,7 @@ dealloc(ChildMonitor* self) {
     Py_CLEAR(self->death_notify);
     Py_CLEAR(self->update_screen);
     Py_CLEAR(self->timers);
+    Py_CLEAR(self->render_func);
     Py_TYPE(self)->tp_free((PyObject*)self);
     while (remove_queue_count) {
         remove_queue_count--;
@@ -253,9 +255,9 @@ do_parse(ChildMonitor *self, Screen *screen, unsigned long child_id) {
     screen_mutex(unlock, read);
 }
 
-static PyObject *
+static void
 parse_input(ChildMonitor *self) {
-#define parse_input_doc "parse_input() -> Parse all available input that was read in the I/O thread."
+    // Parse all available input that was read in the I/O thread.
     size_t count = 0;
     children_mutex(lock);
     while (num_dead_children) {
@@ -297,7 +299,6 @@ parse_input(ChildMonitor *self) {
     if (wait_for < self->repaint_delay) {
         timers_add(self->timers, wait_for, false, Py_None, NULL);
     }
-    Py_RETURN_NONE;
 }
 
 static PyObject *
@@ -321,9 +322,21 @@ mark_for_close(ChildMonitor *self, PyObject *args) {
 #undef DECREF_CHILD
 
 static PyObject*
-main_loop(ChildMonitor UNUSED *self) {
+main_loop(ChildMonitor *self) {
 #define main_loop_doc "The main thread loop"
+    PyObject *ret;
+    double timeout;
+
     while (!glfwWindowShouldClose(glfw_window_id)) {
+        ret = PyObject_CallObject(self->render_func, NULL);
+        if (ret == NULL) return NULL; 
+        else Py_DECREF(ret);
+        glfwSwapBuffers(glfw_window_id);
+        timeout = timers_timeout(self->timers);
+        if (timeout < 0) glfwWaitEvents();
+        else if (timeout > 0) glfwWaitEventsTimeout(timeout);
+        timers_call(self->timers);
+        parse_input(self);
     }
     Py_RETURN_NONE;
 }
@@ -512,7 +525,6 @@ static PyMethodDef methods[] = {
     METHOD(wakeup, METH_NOARGS)
     METHOD(shutdown, METH_NOARGS)
     METHOD(main_loop, METH_NOARGS)
-    METHOD(parse_input, METH_NOARGS)
     METHOD(mark_for_close, METH_VARARGS)
     {NULL}  /* Sentinel */
 };
diff --git a/kitty/data-types.h b/kitty/data-types.h
index e86ef40bf..626644912 100644
--- a/kitty/data-types.h
+++ b/kitty/data-types.h
@@ -279,7 +279,7 @@ PyTypeObject Timers_Type;
 typedef struct {
     PyObject_HEAD
 
-    PyObject *dump_callback, *update_screen, *death_notify;
+    PyObject *dump_callback, *update_screen, *death_notify, *render_func;
     Timers *timers;
     double repaint_delay;
     unsigned int count;
diff --git a/kitty/main.py b/kitty/main.py
index 1c3427010..a0c99eccc 100644
--- a/kitty/main.py
+++ b/kitty/main.py
@@ -23,7 +23,7 @@ from .fast_data_types import (
     GLFW_STENCIL_BITS, Window, change_wcwidth, check_for_extensions,
     enable_automatic_opengl_error_checking, glClear, glClearColor, glewInit,
     glfw_init, glfw_init_hint_string, glfw_set_error_callback,
-    glfw_swap_interval, glfw_terminate, glfw_wait_events, glfw_window_hint
+    glfw_swap_interval, glfw_terminate, glfw_window_hint
 )
 from .layout import all_layouts
 from .shaders import GL_VERSION
@@ -166,11 +166,6 @@ def clear_buffers(window, opts):
     # glfw_swap_interval(1)
 
 
-def dispatch_pending_calls(boss):
-    boss.ui_timers.call()
-    boss.child_monitor.parse_input()
-
-
 def run_app(opts, args):
     setup_opengl(opts)
     load_cached_values()
@@ -212,11 +207,7 @@ def run_app(opts, args):
     boss.start()
     clear_buffers(window, opts)
     try:
-        while not window.should_close():
-            boss.render()
-            window.swap_buffers()
-            glfw_wait_events(boss.ui_timers.timeout())
-            dispatch_pending_calls(boss)
+        boss.child_monitor.main_loop()
     finally:
         boss.destroy()
     del window