Minecraft was fine in every snaphot before this one, but today I opened 15w45a and created a new world and the game started lagging (extreme lag, I was not able to move fluently).

EDIT: A lot of lag also in main menù and world selection menù
Report of launcher:
[16:30:33] [Server thread/INFO]: Starting integrated minecraft server version 15w45a
[16:30:33] [Server thread/INFO]: Generating keypair
[16:30:33] [Server thread/INFO]: Preparing start region for level 0
[16:30:34] [Server thread/INFO]: Preparing spawn area: 1%
[16:30:35] [Server thread/INFO]: Preparing spawn area: 8%
[16:30:36] [Server thread/INFO]: Preparing spawn area: 15%
[16:30:37] [Server thread/INFO]: Preparing spawn area: 20%
[16:30:38] [Server thread/INFO]: Preparing spawn area: 29%
[16:30:39] [Server thread/INFO]: Preparing spawn area: 36%
[16:30:40] [Server thread/INFO]: Preparing spawn area: 43%
[16:30:41] [Server thread/INFO]: Preparing spawn area: 48%
[16:30:42] [Server thread/INFO]: Preparing spawn area: 55%
[16:30:43] [Server thread/INFO]: Preparing spawn area: 61%
[16:30:44] [Server thread/INFO]: Preparing spawn area: 66%
[16:30:45] [Server thread/INFO]: Preparing spawn area: 72%
[16:30:47] [Server thread/INFO]: Preparing spawn area: 80%
[16:30:48] [Server thread/INFO]: Preparing spawn area: 88%
[16:30:49] [Server thread/INFO]: Preparing spawn area: 95%
[16:30:50] [Server thread/INFO]: Changing view distance to 16, from 10
[16:30:50] [Server thread/INFO]: Evas0r[local:E:e7e1d3ee] logged in with entity id 391 at (84.01528158187901, 69.0, 240.6888160596718)
[16:30:50] [Server thread/INFO]: Evas0r joined the game
[16:30:58] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 7613ms behind, skipping 152 tick(s)
[16:31:25] [Server thread/INFO]: Saving and pausing game...
[16:31:25] [Server thread/INFO]: Saving chunks for level 'New World'/Overworld
[16:31:30] [Client thread/INFO]: Using default channel type
[16:31:30] [Client thread/INFO]: Started on 51989
[16:31:30] [Client thread/INFO]: [CHAT] Local game hosted on port 51989
[16:31:33] [Server thread/INFO]: Saving chunks for level 'New World'/Nether
[16:31:33] [Server thread/INFO]: Saving chunks for level 'New World'/The End
[16:31:41] [Server thread/INFO]: [Evas0r: Given [Elytra] * 1 to Evas0r]
[16:31:42] [Client thread/INFO]: [CHAT] Given [Elytra] * 1 to Evas0r
[16:31:50] [Server thread/INFO]: [Evas0r: Set own game mode to Creative Mode]
[16:31:51] [Client thread/INFO]: [CHAT] Your game mode has been updated to Creative Mode
[16:31:53] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 45583ms behind, skipping 911 tick(s)
[16:31:57] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 4435ms behind, skipping 88 tick(s)
[16:32:15] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 4217ms behind, skipping 84 tick(s)
[16:32:30] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 2962ms behind, skipping 59 tick(s)
[16:32:48] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 2992ms behind, skipping 59 tick(s)
[16:33:06] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 2153ms behind, skipping 43 tick(s)
[16:33:22] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 2677ms behind, skipping 53 tick(s)
[16:34:29] [Server thread/INFO]: Evas0r has just earned the achievement [Taking Inventory]
[16:34:29] [Client thread/INFO]: [CHAT] Evas0r has just earned the achievement [Taking Inventory]