Call of textscan or strfind function takes long time for first time while running in loop [matlab 2020b on linux centos]

We are trying to read a file which has repeatedly 9 rows of text followed by 200000 particle trajectories. A piece of code, enough to produce the problem is:

fname = abc.txt;
fid = fopen(fname,'r');
for ii = 1:20
    InputText=textscan(fid,'%s',9,'delimiter','\n');
    ii
    pp = InputText{1};
    Nrows = pp{4} 
    aa =textscan(fid,'%d %d %f %f %f %f', ...    % Read data block
                           'delimiter',',');
end

apparently, to print ii = 1, it takes 10 seconds while rest all calls in loop finish in 1-2 seconds. It clearly indicates that trouble is on first call of textscan and not with subsequent calls.

The same issue is with strfind function if i put in loop.

I checked on matlab and the answers suggest either license issue or graphics issue. I ran matlab with no-desktop and still got the same issue. I checked it with Nvidia and opengl software choice and issue persists.

Kindly help resolving.

[dpb]

    InputText=textscan(fid,'%s',9,'delimiter','\n');
    ii
    pp = InputText{1};
    Nrows = pp{4} 

looks peculiar -- you read as char() data but then use the content as numeric without a conversion operation.

Answer 1

[Walter Roberson]

Specify the file encoding when you do the fopen(), or else it will scan the entire file checking to see if any utf8 is present

[Sanat Kumar Tiwari]

Thanks Walter. It worked.

[dpb]

I'm always forgetting that change in behavior, too...glad your rememberer is better, Walter! :)