On a DEC 5000 PX using the Xtm2d server, plots that contain y-axes
take forever to draw. This appears to be due to a bug in either the
server software or the PX hardware. Below is a context diff for a
patch to X11graph.c (2.1R2 version) that works around this problem. I
think it can safely be applied on any system. Apply it using `patch'.

[If you care about more details, the problem is that the XGetImage call
used in getting character images by the draw_char_up routine takes forever
to get the image from the server when it is called while drawing a plot.
Presumably this has to do with management of resources, since it is not
a problem if this call occurs early in the initialization phase before all
X resources have been claimed. The patch below therefore allocates all
the character images it needs up front.]
-------------------------------------------------------------------------------

*** X11graph.c	Sun Oct 14 09:59:55 1990
--- X11graph.c.new	Mon Jun 17 18:37:46 1991
***************
*** 334,339 ****
--- 334,340 ----
  static GC CharGC, CharEraseGC;
  static GC copy_gc;   /* used to deal with the cfb clipping bug in R3 */
  GC ResizeGC;
+ static XImage *cxi[128]; /* for use in reversing characters */
  
  typedef struct {
    long Object;                                /* elements of window_data */
***************
*** 474,479 ****
--- 475,481 ----
    valuemask = 0; /* ignore XGCValues and use defaults */
    copy_gc = XCreateGC(dpy, RootWindow(dpy, screen), valuemask, &values);
  
+   MakeCharImages();
    MakeWorkPort();
    MakeSymbols();
    MakeGraphCursors();
***************
*** 1632,1637 ****
--- 1634,1660 ----
    }
  }
  
+ static MakeCharImages()
+ {
+   Display *dpy = StX11Display();
+   int screen = StX11Screen();
+   int ascent = GraphFont->max_bounds.ascent;
+   int width = GraphFont->max_bounds.width;
+   int height = GraphFont->max_bounds.ascent + GraphFont->max_bounds.descent;
+   int i;
+   char myChar;
+ 
+   for (i = 0; i < 128; i++) {
+     if (isprint(i)) {
+       myChar = i;
+       XFillRectangle(dpy, CharPM, CharEraseGC, 0, 0, width, height);
+       XDrawString(dpy, CharPM, CharGC, 0, ascent, &myChar, 1);
+       cxi[i] = XGetImage(dpy, CharPM, 0, 0, width, height, AllPlanes, ZPixmap);
+     }
+     else cxi[i] = nil;
+   }
+ }
+ 
  static draw_char_up(gwinfo, myChar, x, y)
       StGWWinInfo *gwinfo;
       char myChar;
***************
*** 1649,1660 ****
    static XPoint *p = nil;
    int n;
  
    if (p == nil) p = (XPoint *) StCalloc(width * height, sizeof(XPoint));
  
!   if (is_allocated(gwinfo)) {
!     XFillRectangle(dpy, CharPM, CharEraseGC, 0, 0, width, height);
!     XDrawString(dpy, CharPM, CharGC, 0, ascent, &myChar, 1);
!     xi = XGetImage(dpy, CharPM, 0, 0, width, height, AllPlanes, ZPixmap);
      d = get_drawable(gwinfo);
      for (i = 0, n = 0; i < width; i++)
        for (j = 0; j < height; j++)
--- 1672,1684 ----
    static XPoint *p = nil;
    int n;
  
+   if (myChar < 0) myChar = 0;
+   if (myChar > 127) myChar = 127;
+ 
    if (p == nil) p = (XPoint *) StCalloc(width * height, sizeof(XPoint));
  
!   if (is_allocated(gwinfo) && cxi[myChar] != nil) {
!     xi = cxi[myChar];
      d = get_drawable(gwinfo);
      for (i = 0, n = 0; i < width; i++)
        for (j = 0; j < height; j++)
***************
*** 1664,1670 ****
  	  n++;
  	}
      XDrawPoints(dpy, d, draw_gc(gwinfo), p, n, CoordModeOrigin);
-     XDestroyImage(xi);
    }
  }
  
--- 1688,1693 ----