SFTP crash

I have just experienced a crash of SFTP 3.0.1016.15, and not sure sure how this happened.
It was more or less out of the blue and the pop up I got before it closed was about some run-time error of a microsoft library.

Does SFTP keep getting slower as it uploads? Does it keep some logs in memory that accumulates as it is being used? Because maybe it was just variations in my internet speed but when I restarted SFTP 3.0.1016.15 after the crash, it seemed to zip along much faster ...

Thanks,

Nik C