Help improving performance of my phase shifting fft/ifft script tia sal22

[Rick T]

Help improving performance of my fft/ifft script tia sal22 

Greetings All 

I have a file that I perform a phase shift on a given array 
and it works, but it takes about 23+ seconds to phase shift the signal 1 degree and I'm doing this 360 times.  Which will take 70mins to finish 1 signal

I need to keep fs at 44100 due to the fact that it's audio thats being phase shifted

Can anyone tell me how I can improve the speed of this script? or 
recommend another way of doing this to improve performace? 

example file: 

%speed very slow question

%Phase shift signal using fft and ifft

clc,clear,tic,clf

fs=44100;

dt=1/fs;

len=1; %view 1 sec

t=0:dt:(len-dt);

t=t';

f=2; % frequency number 2.2 doesn't work whole numbers only

y_1eq=[];y_1fft=[];

startphase=1;

incrphase=1;

endphase=180; %max freq to go to

sig=sin(2*pi*f*t);

N = length(sig); %N = length(t);

fprintf('\n building array from equation\n');

for ii=startphase:incrphase:endphase

clk=clock;

%Define a phase shift in rads

DtoR=(ii)*pi/180; %Degree to Radians

p=DtoR; %-pi/4;

num_samp = round((fs/f)*(p/(2*pi)));

%Get the FFT of the signal

z=fft(sig);

%Delay each fft component

for k=1:length(z)

w = 2*pi/N*(k-1);

spec(k)=z(k)*exp(-j*w*num_samp);

spec=spec';

end;

%Get the new signal

newsig=real((ifft(spec)));

y_1fft=[y_1fft(:,:);newsig(:,:)]; %append array of next phase change signal

fprintf('\n %3.2fdeg phase out of %6.2fdeg phase finished in -- %4.4fsec or %4.4fmins\n',ii,endphase, etime(clock, clk),etime(clock,clk)/60);

t1=etime(clock,clk);

fprintf('- time left -%4.4fsec- or -%4.4fmins- or -%4.4fhours-\n',(endphase-ii)*t1*1/incrphase,(endphase-ii)*t1*1/incrphase/60,(endphase-ii)*t1*1/incrphase/3600);

fprintf('- elapsed time -%4.4fsec- or -%4.4fmins- or -%4.4fhours-\n',toc,toc/60,toc/3600);

%plot

axis([-1 fs -1 1])

plot(newsig)

axis([-1 fs -1 1])

grid on

title(['Phase Shift is ',num2str(ii),' degrees'])

pause(.001)

end;

fprintf('- Completed in -%4.4fsec- or -%4.4fmins- or -%4.4fhours-\n',toc,toc/60,toc/3600);

tia sal22