A lot of things are not right, and there are a lot of bugs.. Most of the API is screwed up. They changed how mob targeting/attacking works, meaning Aikar has to rework the Survival update to fix the bugs they added. Nether Fortresses require an update, as currently they're a bit bonkers. Hopefully this will get fixed soon. (By Mojang) Bukkit and Spigot has a ton of bugs - We have to wait for most the bugs to be fixed. These are Minecraft Server enhancements, which usually bring down lag, and improve performance. Usually, the first few versions of these that come out tend to be buggy, so we end up having to wait on them to fix that. Then, Aikar improves upon them, while updating our version of Minecraft Server enhancements. I know waiting sucks, but Aikar has been tackling as many issues as he can, so that way we can update to 1.6 as soon as possible. Please do try to be patient.
Thanks for the update, and as usual, I'm fine with waiting on Aikar to get everything up to EMC grade. I'm just glad we won't have to worry about animals escaping their containment anymore. They've already fixed that and have the update set to come out on Monday. https://mojang.atlassian.net/browse/MC-16761