Write function very slow for certain filenames containing "_" but very fast without it.

[JAQuent]

I encountered a very weird issue while using the toolbox on Ubuntu (but presumably this is also the reason why it takes so long to write stuff on our cluster).

When I am trying write to a .nii file using the write() function I get very different writing speeds depending on the name of the file everything else being the same.

Base code

data = nifti_data_obj;
data.dat = modelmd;
data.fullpath = file_name;
write(data,'overwrite');

If the file name is test.nii, test_test.nii or even TYPEBFITHRF.nii , it is very fast (01 minutes, 01.632 seconds). However if I use the name TYPEB_FITHRF.nii it takes so long to write the 13.9 GB file that in the testing process I never finished it. To give you an idea how slow: After 3 minutes, TYPEB_FITHRF.nii is still only 39.7 MB in file size.

Unfortunately I am not very versed in MATLAB so I have no idea what's going on.