Is there a faster way to import lists other than just the regular import file on the software
is the a ftp function which would enable faster importing
Subscriber details are held in the DB not in flat file. The import method is the only way. How many are you trying to import and how long is it taking?
If you already have them in a MySQL database and you can make that available to be connected to remotely from the MW server I would do that.
If not you will have to do them via CSV files, approximately 260 is my guess, set you memory usage to the max you can allow on your server, keeping in mind to leave sufficient for the OS and anything you have running. Then set the "Import at once" to 5000 and the pause to 1 second. Set the check mime type to NO.
I would then run some imports and see what the performance is like. On subsequent imports try increasing/decreasing the batch number and the pause greater to see which exact settings work best on your server. Much of this is to do with your server power and setup than it is to do with MW.