Since it appears you are also making the files... have you thought about using the SDF instead of delimiting with a tab?

COPY TO Myfile.txt TYPE SDF


>Hi everyone,
>
>I have a huge text file (~100 000 records with ~50-60 fields), Tab delimited. I need to remove all double quotations from this file.
>
>This is the algorithm, we used. It doesn't work on big files - we have an error: "String is too big to fit".
>
>What else could you suggest besides low-level functions?
>
>

>lntxtfiles=adir(laTxtFiles, lcPattern) && Retrieve list of text files
>
>*--------------------------------------------------------------------------
>* -- loop through the array and perform string transformations in each text file
>*--------------------------------------------------------------------------
>create cursor lcTempCursor ;
>                (WorkField M)
>append blank
>
>for i=1 to lnTxtFiles
>    lcFileName=lcPath+laTxtFiles[i,1]
>    lcSendFileName = lcPath+ojc.CurState+'\'+left(laTxtFiles[i,1],4)+'.txt'
>    if file(lcSendFileName)
>        erase (lcSendFileName)
>    endif
>        append memo WorkField from (lcFileName) overwrite
>     if !empty(alltrim(WorkField))
>          replace WorkField with strtran(WorkField,'"','')
>          copy memo WorkField to (lcSendFileName)
>     endif
>next