Wasn't that released like four or five days ago together with the flash update as well? Unfortunately my build is already 10586.3, which means it contains that update (it probably installed it during the update process) and the slow login problem persists. After a fast boot it sits on the welcome screen for 10-15 seconds with the spinning circle. Everything i tried (credential management, local account, etc) didn't do jack so I was hoping that update you were talkin about was some new 0day hotfix..guess i'll have to wait a little longer to get that fixed, if it ever will..
You may well be right about the release date. I honestly don't know, because I was having issues with the MS Upgrade not showing up on my desktop computer. I tried re-setting Windows Update, everything that I read about on this forum, but the upgrade still wouldn't show. My last chance effort was to restore a system image from about a week ago, and BAM, that did the trick. The upgrade to 1115 showed, and installed, which was day before yesterday. The KB3105211 did not show up until a day later, which was yesterday, for me... The result was as I posted, things back to normal, as far as login issues are concerned. Just a shot in the dark here, but you might try to get that KB and do a re-install of it, to see if it helps you at all. If it does, please post back here, so that other members will know.