kvirc has a bug in their sendack() routine when its on ssl, it will be fixed sooner or later. If they dont fix it some time, I 'll help them. There are also private irssi scripts floating around to make it work with ssl. Anyhow I have a custom irc client that supports ssl, I practically have the same dcc transfer speeds with ssl as without it. When i use mirc with ssl wrapping im far away from whats possible, but at least using mirc 6.21 allows me to get speeds of almost 1mb/s. Im no rookie, im software developer myself (not just MSL lol).
I let a handful of other people test the script on 7.x and 6.x with simply the same verdict.
If your on IRC, hook me up and I'll come by and give u some working ssl sends if u want.
I tested 2 threads with ssl on 6.21 from the same user which didnt cause any speedloss on the first get. the 2nd get had the same speed as the first one, 800kb/s~.
