I have a server running with 14w30c. When I visit my overworld villager breeding center, where I have 500 villagers. Most of the them stacked in a single location. The server crashes periodically. Here is one of the error messages from the crash. and a little bit of the messages leading up to the crash.

[15:47:05] [Server thread/WARN]: Can't keep up! Did the system time change, or i
s the server overloaded? Running 7870ms behind, skipping 157 tick(s)
[15:47:28] [Server thread/WARN]: Can't keep up! Did the system time change, or i
s the server overloaded? Running 2719ms behind, skipping 54 tick(s)
[15:48:22] [Server Watchdog/FATAL]: A single server tick took 33.79 seconds (sho
uld be max 0.05)
[15:48:22] [Server Watchdog/FATAL]: Considering it to be crashed, server will fo
rcibly shutdown.
[15:48:22] [Server Watchdog/ERROR]: This crash report has been saved to: C:\Game
s\Minecraft Server (Vanilla)\.\crash-reports\crash-2014-07-29_15.48.22-server.tx
t
[15:48:22] [Server Shutdown Thread/INFO]: Stopping server

On 1.7.x I would not have issues of this type unless the entity count was >1000. And then the server would be laggy, but wouldn't crash.