GIF speed not as expected! Help!

Hello. I am trying to generate a GIF of a growing bar. However, the speed of the generating gif is really slow, and I don't understand how to make it faster. The 'DelayTime' is set to 0, and when the animation is generated in MATLAB is looks really fine. However, when I open the bar.gif, the animation is not fluid at all. This is the code

%draw rectangle and lambda
clear;
figure();
rectangle('Position',[0 2 10 1]);
axis off
set(gcf,'Position',[ -901   789   579    70])
t=0:0.05:3
l=1; a=0.5 
p=@(t,l,a) 1-(1-a).*exp(-l.*t); 
x=[0 0 10 10];
y=[2 3 3 2]; 
patch(x,y,'white');
frame=getframe(gca); im=frame2im(frame); 
[imind,cm] = rgb2ind(im,256); 
filename='bar.gif';
imwrite(imind,cm,filename,'gif','DelayTime',0.5, 'Loopcount',inf);

for tt=1:length(t)
    pt=p(t(tt),l,a);
    x=[0 0 10.*pt 10.*pt];
    patch(x,y,'green');
   % pause(.01); drawnow;

       frame(tt)=getframe(gca);
  end 
  for tt=1:length(t)

   im=frame2im(frame(tt)); 
       [imind,cm] = rgb2ind(im,256);
       imwrite(imind,cm,filename, 'gif','DelayTime',0,'WriteMode','append');
  end

[John D'Errico]

@DA Huang: Please don't answer a question with your own question. Use comments to make a comment.

Moved an answer by Da Huang into a comment:

"Have you solve this problem?"

Answer 1

[Utpal Kumar]

Edited and the delay time has been set to 0.1 seconds:

%draw rectangle and lambda
  clear;
  figure();
  rectangle('Position',[0 2 10 1]);
  axis off
  set(gcf,'Position',[ -901   789   579    70])
  t=0:0.05:3
  l=1; a=0.5 
  p=@(t,l,a) 1-(1-a).*exp(-l.*t); 
  x=[0 0 10 10];
  y=[2 3 3 2]; 
  patch(x,y,'white');
  frame=getframe(gca); im=frame2im(frame); 
  [imind,cm] = rgb2ind(im,256); 
  filename='bar.gif';
  imwrite(imind,cm,filename,'gif','DelayTime',0.1, 'Loopcount',inf);
  for tt=1:length(t)
      pt=p(t(tt),l,a);
      x=[0 0 10.*pt 10.*pt];
      patch(x,y,'green');
     % pause(.01); drawnow;
         frame(tt)=getframe(gca);
    end 
    for tt=1:length(t)
     im=frame2im(frame(tt)); 
         [imind,cm] = rgb2ind(im,256);
         imwrite(imind,cm,filename, 'gif','DelayTime',0.1,'WriteMode','append');
    end

[darova]

I just removed this line:

set(gcf,'Position',[ -901   789   579    70])

And it works ok for me

[Diptangshu Paul]

How is delaytime 0.1 faster than delaytime 0?