The 2.5 release being mentioned afaik was released as a beta as such. However one thing to try is setting ratelimit=0 in the DNAS config which then disables a number of the advert related handling changes that were introduced into the 2.5 builds (i.e. if you're not using the DNAS+ / advert system then it's better to set that option to get back to a more 2.4.7-like behaviour).
Additionally, i believe the option I added (when I was involved with SC development) was called ratelimitwait which was a default of a few seconds (5 maybe) which allows that much of the stream to be sent to the listener un-restricted before the stuff I've mentioned above kicks in if that option is enabled. it accepts second values so is something else to try out. Tweaking that can help with connection times (along with the overall networking buffer as per the docs shipped with the DNAS).
Dunno if any of that will be helpful (considering how late I am to see this), otherwise probably going back to 2.4.7 is the better option (and if the fancy takes you, complaining to SC about such issues so whatever dev team there now is might just consider fixing things or not, heh.