I am using a VB Script that I got from somewhere on this forum for ages now and have built myself a user object that contains things I usually need. I have used it regularly for large datasets in a similar size (around 10.000 lines of csv)
You can input any text, select a folder from a dialog, enter a filename, file ending and then save the file.
It has worked well for me for the last few years.
save_text.gh (11.9 KB)
ps: the C# script is so it “remembers” the Folder location that you picked even after restart. Plus there is also a boolean input to append data, but I have never needed that.