Decrypt local file

Hi
I just started to use WinSCP, could you advice if there is any option to encrypt/decrypt local files?
I have home SFTP so I can access them straight away. It would be better to encrypt/decrypt locally without sending them through WiFi with small speed.
Regards

What does encryption (and what kind of encryption?) have to do with the "small speed"? Don't you want to compress the files instead?

Encryption - built in AES-256.
I can locally connect drive and copy encrypted files with 100mb+ speed.
Via WiFi just 10mb/s