diff --git a/api/graphics_api.C b/api/graphics_api.C
index 8a2d0e5dab..5858ec946e 100755
--- a/api/graphics_api.C
+++ b/api/graphics_api.C
@@ -28,6 +28,9 @@ extern DWORD WINAPI win_graphics_event_loop( LPVOID duff );
 HANDLE graphics_threadh=NULL;
 #endif
 
+#ifdef __APPLE_CC__
+#include "mac_app_opengl.h"
+#endif
 
 #include <string.h>
 #include <stdarg.h>
@@ -37,13 +40,12 @@ HANDLE graphics_threadh=NULL;
 #endif
 
 #include "parse.h"
+#include "util.h"
 #include "app_ipc.h"
-#include "graphics_api.h"
 #include "error_numbers.h"
+#include "boinc_api.h"
+#include "graphics_api.h"
 
-#ifdef __APPLE_CC__
-#include "mac_app_opengl.h"
-#endif
 
 #ifdef _WIN32
 HANDLE hQuitEvent;
@@ -158,6 +160,61 @@ int boinc_finish_opengl() {
     return 0;
 }
 
+void throttled_app_render(int x, int y, double t) {
+    static double total_render_time = 0;
+    static double time_until_render = 0;
+    static double last_now = 0;
+    static double elapsed_time = 0;
+    double now, t0, t1, diff, frac, m;
+    bool ok_to_render;
+
+    // the following should be passed in via prefs
+    double max_fps = 1;
+    double max_gfx_cpu_frac = 0.2;
+
+    ok_to_render = true;
+    now = dtime();
+    diff = now - last_now;
+    last_now = now;
+    if (diff > 1) diff = 0;     // handle initial case
+
+    // enforce frames/sec restriction
+    //
+    if (max_fps) {
+        time_until_render -= diff;
+        if (time_until_render < 0) {
+            time_until_render += 1./max_fps;
+        } else {
+            ok_to_render = false;
+        }
+    }
+
+    // enforce max CPU time restriction
+    //
+    if (max_gfx_cpu_frac) {
+        elapsed_time += diff;
+        if (elapsed_time) {
+            frac = total_render_time/elapsed_time;
+            if (frac > max_gfx_cpu_frac) {
+                ok_to_render = false;
+            }
+        }
+    }
+
+    // render if allowed
+    //
+    if (ok_to_render) {
+        if (max_gfx_cpu_frac) {
+            boinc_cpu_time(t0, m);
+        }
+        app_render(x, y, t);
+        if (max_gfx_cpu_frac) {
+            boinc_cpu_time(t1, m);
+            total_render_time += t1 - t0;
+        }
+    }
+}
+
 #ifdef HAVE_GL_LIB
 // Custom GL "Print" Routine
 GLvoid glPrint(GLuint font, const char *fmt, ...) {
diff --git a/api/graphics_api.h b/api/graphics_api.h
index 256d1b4627..c690a76b27 100755
--- a/api/graphics_api.h
+++ b/api/graphics_api.h
@@ -8,9 +8,11 @@
 #ifndef HAVE_OPENGL_GL_H
 #define HAVE_OPENGL_GL_H
 #endif
+#include <Carbon/Carbon.h>
 #endif
 
 #ifdef _WIN32
+#include <windows.h>
 #ifndef HAVE_GL_LIB
 #define HAVE_GL_LIB 1
 #endif
@@ -68,15 +70,10 @@
 #include "x_opengl.h"
 #endif
 
-#ifdef __APPLE_CC__
-#include <Carbon/Carbon.h>
-#endif
-
 // The API (functions called by the app)
 extern int boinc_init_opengl();
 extern int boinc_finish_opengl();
 extern GLvoid glPrint(GLuint font, const char *fmt, ...);
-extern GLenum ReSizeGLScene(GLsizei width, GLsizei height);
 
 // Functions that must be supplied by the app
 //
@@ -88,6 +85,7 @@ extern void app_resize(int width, int height);
 //
 extern GLenum InitGL(GLvoid);
 extern GLenum ReSizeGLScene(GLsizei width, GLsizei height);
+extern void throttled_app_render(int, int, double);
 
 #ifdef _WIN32
 extern HANDLE hQuitEvent;
diff --git a/api/windows_opengl.C b/api/windows_opengl.C
index d08c0b7c5c..613c161b83 100755
--- a/api/windows_opengl.C
+++ b/api/windows_opengl.C
@@ -1,5 +1,9 @@
-// Event loop and support functions for BOINC applications w/ graphics.
-// Is any of this related to or dependent on OpenGL??
+// Event loop and support functions for Windows versions
+// of BOINC applications w/ graphics.
+// Platform-independent code should NOT be here.
+//
+// TODO: Is any of this related to or dependent on OpenGL??
+// Why not make it independent of OpenGL?
 //
 
 /*		This Code Was Created By Jeff Molofee 2000
@@ -137,9 +141,8 @@ void SetMode(int mode) {
 	hWnd = CreateWindowEx(dwExStyle, "BOINC_OpenGL", aid.app_name,
 		dwStyle|WS_CLIPSIBLINGS|WS_CLIPCHILDREN, WindowRect.left, WindowRect.top,
 		WindowRect.right-WindowRect.left,WindowRect.bottom-WindowRect.top,
-		NULL, NULL, hInstance, NULL);
-
-
+		NULL, NULL, hInstance, NULL
+    );
 
 	SetForegroundWindow(hWnd);
 
@@ -241,27 +244,26 @@ LRESULT CALLBACK WndProc(	HWND	hWnd,			// Handle For This Window
 			}
 			if (current_graphics_mode == MODE_HIDE_GRAPHICS) return 0;
 
-			if(dtime()-starttime>1./fps)
-			{
-				GetClientRect(hWnd, &rt);
-				width = rt.right-rt.left;
-				height = rt.bottom-rt.top;
+            // TODO: remove width, height from API
+            //
+		    GetClientRect(hWnd, &rt);
+			width = rt.right-rt.left;
+			height = rt.bottom-rt.top;
 
 #ifdef DRAW_WITH_DLL
-				float* data;
-				int data_size=100;
-				data=(float*)malloc(sizeof(float)*data_size);
-				for(int i=0;i<data_size;i++)
-				{
-					data[i]=float(rand()%1000/1000.);
-				}
-				vis_render(width,height,dtime(),data,data_size);
+			float* data;
+			int data_size=100;
+			data=(float*)malloc(sizeof(float)*data_size);
+			for(int i=0;i<data_size;i++)
+			{
+				data[i]=float(rand()%1000/1000.);
+			}
+			vis_render(width,height,dtime(),data,data_size);
 #else
-				app_render(width, height, dtime());			
+			throttled_app_render(width, height, dtime());			
 #endif
-				starttime=dtime();
-				SwapBuffers(hDC);
-			}		
+			starttime=dtime();
+			SwapBuffers(hDC);
 			return 0;
 	}