Hello, I am relatively new to Cairo and this is my first time using the mailing list, so please be nice. I'm currently using Cairo to create a HUD interface in a flight simulator, and I'm encountering significant drawing performance issues in certain situations.  Since my application is a HUD, it needs to be redrawn very quickly, and the total drawing time must not exceed 16ms in order to maintain a smooth 60fps experience. Let me give you some specifics about my system:  I'm using multiple windows PCs, ranging from a single core Pentium M laptop 1gig ram to a quad core 4gig ram desktop simulator, and this issue occurs on all of them.  I'm using Visual C++ in Visual Studio 2008 Professional and am working with the current 1.8.0 build of Cairo.  I got the binaries and includes from the GTK+ for Windows site. My application draws many things onto the screen and is generally very fast, but I've encountered situations where it takes absurdly long to draw something very simple (i.e. 150ms to draw a straight line).  In particular this performance issue generally occurs when long lines are drawn at an angle across the screen, or when large shapes, such as a call to cairo_rectangle to render a full screen (non-filled) square are drawn.  I will further clarify a few cases where I've noticed performance issues. First, I will share how I have set up my cairo environment.  I'm using Cairo to render to an image buffer using 8 bit alpha.  The reason for this is that I'm using OpenGL as a front end to examine the alpha values in the buffer (either on or off) and draw each individual pixel to the screen in a single color.  If this seems convoluted to you, just accept it for now.  Here's the code I use to set up the context: cairo_surface_t *surface = cairo_image_surface_create(CAIRO_FORMAT_A8, 1280, 1024); cairo_t *cr = cairo_create(surface); cairo_set_source_rgba(cr, 0.0, 0.0, 0.0, 1.0); cairo_select_font_face (cr, "Sans", CAIRO_FONT_SLANT_NORMAL, CAIRO_FONT_WEIGHT_BOLD); cairo_set_antialias(cr, CAIRO_ANTIALIAS_NONE); Now, on to the issues.  Note that the following timing is done on the single core Pentium M laptop, but I've noticed similar behavior on the quad core, and the fact that there is such a large difference between the cases concerns me: 1. The first issue I mentioned having to do with long, angled lines is manifested in the following way:  When I draw a single 5 pixel wide line horizontally across the screen like so, it takes less than 1ms to draw: cairo_set_line_width(cr, 5.0); cairo_move_to(cr, 50.0, 50.0); cairo_line_to(cr, 1230.0, 50.0); cairo_stroke(cr); However, if I rotate the line to a 45 degree angle, it takes anywhere from 80 to 200ms to draw: cairo_rotate(45.0*3.14159/180.0); cairo_set_line_width(cr, 5.0); cairo_move_to(cr, 50.0, 50.0); cairo_line_to(cr, 1230.0, 50.0); cairo_stroke(cr); At first I thought this might be due to antialiasing being enabled (which might have a noticeable performance effect on long slanted lines), but I added the specific cairo_set_antialias(cr, CAIRO_ANTIALIAS_NONE); function call when setting up the context, and it seems to make no difference. 2.  The second issue has to do with the seeming fact that calling cairo_rectangle is much slower than drawing individual lines and rendering each one separately.  For example, the following rectangle call takes over 200ms: cairo_set_line_width(cr, 5.0); cairo_rectangle(cr, 50, 50, 1180, 924); cairo_stroke(cr); ...while drawing and rendering each line of the rectangle separately takes 0-50ms, whihc is still longer than I'd like, but significantly less than rendering the whole rectangle at once: cairo_set_line_width(cr, 5.0); cairo_move_to(cr, 50.0, 50.0); cairo_line_to(cr, 1230.0, 50.0); cairo_stroke(cr); cairo_move_to(cr, 1230.0, 50.0); cairo_line_to(cr, 1230.0, 974.0); cairo_stroke(cr); cairo_move_to(cr, 1230.0, 974.0); cairo_line_to(cr, 50.0, 974.0); cairo_stroke(cr); cairo_move_to(cr, 50.0, 974.0); cairo_line_to(cr, 50.0, 50.0); cairo_stroke(cr); I'm hoping someone can shed some light on these issues.  I have no doubt that you will receive better render times than my single core laptop did, but do you notice differences in timing between the cases?  Does it have to do with the way I'm setting up my context, or the particular cairo build I'm using, or is there some function I should be using?  Could it have to do with the fact that I don't always supply even integer values to the drawing functions (like I did in the examples) so that Cairo is having trouble drawing between pixels?  I'm hoping the answer is not that Cairo is just too slow to maintain 60fps in simple 2D applications.  Any suggestions or help would be much appreciated Thanks!