OPR-computation-related linear algebra problem

[Ether]

Just installed Octave3.6.4_gcc4.6.2_20130408 on this computer.

Results:

GNU Octave, version 3.6.4

Octave was configured for "i686-pc-mingw32".

octave:1> tic; d = load('k:/MyOctave/d.dat'); toc
Elapsed time is 0.0625 seconds

octave:2> tic; N = load('k:/MyOctave/N.dat'); toc
Elapsed time is 90.0469 seconds

octave:3> tic; r = N \ d; toc
Elapsed time is 1.03125 seconds

octave:4> tic; r = N \ d; toc
Elapsed time is 0.953125 seconds

octave:5> tic; Ns = sparse(N); toc
Elapsed time is 0.0625 seconds
octave:6> tic; rs = Ns \ d; toc
Elapsed time is 0.1875 seconds

octave:7> tic; Ns = sparse(N); toc
Elapsed time is 0.046875 seconds
octave:8> tic; rs = Ns \ d; toc
Elapsed time is 0.171875 seconds

Anybody know why Octave takes so long to load N ?

Load N times, all on the same computer:

Delphi....0.6 seconds

C.........1.3 seconds

SciLab....1.7 seconds

RLab......3.7 seconds

Python....6.5 seconds

Octave...90.0 seconds