I recently notice that there is an extreme slowdown in my version of Matlab while computing an SVD when the size of the matrix crosses some threshold. I came up with the following example that demonstrates my issue:
N = [10000 11000 12000 13000];
for i = 1:4
A = randn(N(i),3);
tic;
[U,S,V] = svd(A,0);
toc;
end
When I run this in Matlab R2024b (macOS Apple silicon), the output is:
Elapsed time is 0.000396 seconds.
Elapsed time is 0.000275 seconds.
Elapsed time is 0.000264 seconds.
Elapsed time is 0.083150 seconds.
Of course the exact numbers vary trial to trial, but the speed for the last run (where N = 13000) is consistently orders of magnitude slower.
When I run this same code on Matlab R2024b (Intel processor) on the same computer, this slow down does not happen. I was able to replicate this issue across two different Macs (one with M1 and another with M3) and different versions of Matlab (going back to R2023b).
Any idea why this might be happening in the silicon version?
Edit: I’m running macOS 15.1.1I recently notice that there is an extreme slowdown in my version of Matlab while computing an SVD when the size of the matrix crosses some threshold. I came up with the following example that demonstrates my issue:
N = [10000 11000 12000 13000];
for i = 1:4
A = randn(N(i),3);
tic;
[U,S,V] = svd(A,0);
toc;
end
When I run this in Matlab R2024b (macOS Apple silicon), the output is:
Elapsed time is 0.000396 seconds.
Elapsed time is 0.000275 seconds.
Elapsed time is 0.000264 seconds.
Elapsed time is 0.083150 seconds.
Of course the exact numbers vary trial to trial, but the speed for the last run (where N = 13000) is consistently orders of magnitude slower.
When I run this same code on Matlab R2024b (Intel processor) on the same computer, this slow down does not happen. I was able to replicate this issue across two different Macs (one with M1 and another with M3) and different versions of Matlab (going back to R2023b).
Any idea why this might be happening in the silicon version?
Edit: I’m running macOS 15.1.1 I recently notice that there is an extreme slowdown in my version of Matlab while computing an SVD when the size of the matrix crosses some threshold. I came up with the following example that demonstrates my issue:
N = [10000 11000 12000 13000];
for i = 1:4
A = randn(N(i),3);
tic;
[U,S,V] = svd(A,0);
toc;
end
When I run this in Matlab R2024b (macOS Apple silicon), the output is:
Elapsed time is 0.000396 seconds.
Elapsed time is 0.000275 seconds.
Elapsed time is 0.000264 seconds.
Elapsed time is 0.083150 seconds.
Of course the exact numbers vary trial to trial, but the speed for the last run (where N = 13000) is consistently orders of magnitude slower.
When I run this same code on Matlab R2024b (Intel processor) on the same computer, this slow down does not happen. I was able to replicate this issue across two different Macs (one with M1 and another with M3) and different versions of Matlab (going back to R2023b).
Any idea why this might be happening in the silicon version?
Edit: I’m running macOS 15.1.1 svd, mac, memory, speed MATLAB Answers — New Questions

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