Exports can last hours depending on the number of files. Changing the format can decrease the time it takes.
There are two types of reports Windows Client (WC) can generate - formatted report and raw data report (see attached "Output Format.png").
Generation of a raw data report (in red oval in "Output Format.png") is significantly faster because the output is not formatted. Generating a formatted report for 68 000 records is bound to be slow no matter how much RAM your computer possesses.