diff --git a/c_src/main.c b/c_src/main.c
index 87fe063..167be27 100644
--- a/c_src/main.c
+++ b/c_src/main.c
@@ -30,7 +30,7 @@ int main(int argc, char **argv)
   driver_data_t data = {0};
 
   // super simple arg check
-  if (argc != 10) {
+  if (argc != 11) {
     log_error("Wrong number of parameters");
     return -1;
   }
@@ -41,10 +41,11 @@ int main(int argc, char **argv)
   g_opts.global_opacity = atoi(argv[3]);
   g_opts.antialias = atoi(argv[4]);
   g_opts.debug_mode = atoi(argv[5]);
-  g_opts.width = atoi(argv[6]);
-  g_opts.height = atoi(argv[7]);
-  g_opts.resizable = atoi(argv[8]);
-  g_opts.title = argv[9];
+  g_opts.debug_fps = atoi(argv[6]);
+  g_opts.width = atoi(argv[7]);
+  g_opts.height = atoi(argv[8]);
+  g_opts.resizable = atoi(argv[9]);
+  g_opts.title = argv[10];
 
   // init the hashtables
   init_scripts();
diff --git a/c_src/scenic/comms.c b/c_src/scenic/comms.c
index 7cef107..d589736 100644
--- a/c_src/scenic/comms.c
+++ b/c_src/scenic/comms.c
@@ -21,21 +21,14 @@ The caller will typically be erlang, so use the 2-byte length indicator
 #include "script.h"
 #include "utils.h"
 
-// handy time definitions in microseconds
-#define MILLISECONDS_8 8000
-#define MILLISECONDS_16 16000
-#define MILLISECONDS_20 20000
-#define MILLISECONDS_32 32000
-#define MILLISECONDS_64 64000
-#define MILLISECONDS_128 128000
-
 // Setting the timeout too high means input will be laggy as you
 // are starving the input polling. Setting it too low means using
 // energy for no purpose. Probably best if set similar to the
 // frame rate of the application
-#define STDIO_TIMEOUT MILLISECONDS_32
+#define STDIO_TIMEOUT 32
 
 extern device_info_t g_device_info;
+extern device_opts_t g_opts;
 
 //=============================================================================
 // raw comms with host app
@@ -407,6 +400,14 @@ void receive_crash()
 //---------------------------------------------------------
 void render(driver_data_t* p_data)
 {
+  // Setup FPS calc
+  static int64_t start_real = 0;
+  static int64_t time_remaining = -1;
+  static clock_t render_fps = 0;
+  static uint32_t frames = 0;
+
+  clock_t begin_frame = clock();
+
   // prep the id to the root scene
   sid_t id;
   id.p_data = "_root_";
@@ -428,6 +429,27 @@ void render(driver_data_t* p_data)
   }
 
   device_end_render(p_data);
+  clock_t end_frame = clock();
+  clock_t delta_ticks = end_frame - begin_frame;
+
+  if ((g_opts.debug_fps > 1) && (delta_ticks > 0)) {
+    render_fps = CLOCKS_PER_SEC / delta_ticks;
+    log_debug("render_fps (cpu time): %d", render_fps);
+  }
+
+  frames++;
+
+  int64_t end_real = monotonic_time();
+  int64_t delta_real = (end_real - start_real);
+  start_real = end_real;
+  time_remaining -= delta_real;
+
+  if ((g_opts.debug_fps > 0) && (time_remaining <= 0)) {
+    log_info("real_fps: %d", frames);
+    start_real = monotonic_time();
+    time_remaining = 1000;
+    frames = 0;
+  }
 
   // all done
   send_ready();
diff --git a/c_src/scenic/scenic_types.h b/c_src/scenic/scenic_types.h
index 4858a73..fef12c6 100644
--- a/c_src/scenic/scenic_types.h
+++ b/c_src/scenic/scenic_types.h
@@ -61,6 +61,7 @@ typedef struct {
 typedef struct {
   // options from the command line
   int debug_mode;
+  int debug_fps;
   int layer;
   int global_opacity;
   int antialias;
diff --git a/lib/driver.ex b/lib/driver.ex
index b2890e9..990a44a 100644
--- a/lib/driver.ex
+++ b/lib/driver.ex
@@ -26,6 +26,7 @@ defmodule Scenic.Driver.Local do
     opacity: [type: :integer, default: @default_opacity],
     debug: [type: :boolean, default: false],
     debugger: [type: :string, default: ""],
+    debug_fps: [type: :integer, default: 0],
     antialias: [type: :boolean, default: true],
     calibration: [
       type: {:custom, __MODULE__, :validate_calibration, []},
@@ -214,6 +215,7 @@ defmodule Scenic.Driver.Local do
       end
 
     {:ok, debugger} = Keyword.fetch(opts, :debugger)
+    {:ok, debug_fps} = Keyword.fetch(opts, :debug_fps)
     {:ok, layer} = Keyword.fetch(opts, :layer)
     {:ok, opacity} = Keyword.fetch(opts, :opacity)
 
@@ -227,7 +229,7 @@ defmodule Scenic.Driver.Local do
       end
 
     args =
-      " #{internal_cursor} #{layer} #{opacity} #{antialias} #{debug_mode}" <>
+      " #{internal_cursor} #{layer} #{opacity} #{antialias} #{debug_mode} #{debug_fps}" <>
         " #{width} #{height} #{resizeable} \"#{title}\""
 
     # open and initialize the window
diff --git a/test/driver_test.exs b/test/driver_test.exs
index 316f7d1..ad9dc55 100644
--- a/test/driver_test.exs
+++ b/test/driver_test.exs
@@ -9,6 +9,7 @@ defmodule Scenic.Driver.LocalTest do
       opacity: 1,
       debug: false,
       debugger: "",
+      debug_fps: 0,
       antialias: true,
       calibration: [{"calibration_name", {{0, 0, 0}, {0, 0, 0}}}],
       position: [