Mobs freeze

If that happens only for skeletons, that is duplicate of MC-91290
If it happens for all mobs, maybe it is a problem of your own local server. Try force crashing by pressing F3+C long. Attach the crash log.

Not only skeletons...

Minecraft Crash Report ----
// On the bright side, I bought you a teddy bear!

Time: 26.01.16. 17:27
Description: Manually triggered debug crash

java.lang.Throwable
at bcc.ay(SourceFile:1682)
at bcc.s(SourceFile:1603)
at bcc.au(SourceFile:949)
at bcc.a(SourceFile:390)
at net.minecraft.client.main.Main.main(SourceFile:122)

A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

– Head –
Stacktrace:
at bcc.ay(SourceFile:1682)

– Affected level –
Details:
Level name: MpServer
All players: 1 total; [bmp['Wyrdfell'/281, l='MpServer', x=1622,50, y=70,00, z=-1151,94]]
Chunk stats: MultiplayerChunkCache: 529, 529
Level seed: 0
Level generator: ID 00 - default, ver 1. Features enabled: false
Level generator options:
Level spawn location: World: (216,64,256), Chunk: (at 8,4,0 in 13,16; contains blocks 208,0,256 to 223,255,271), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Level time: 5311969 game time, 7415132 day time
Level dimension: 0
Level storage version: 0x00000 - Unknown?
Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false
Forced entities: 181 total; [wc['Sheep'/519, l='MpServer', x=1661,66, y=70,00, z=-1205,16], wc['Sheep'/520, l='MpServer', x=1650,09, y=71,00, z=-1187,53], yr['Enderman'/62989, l='MpServer', x=1626,50, y=15,00, z=-1084,50], wc['Sheep'/533, l='MpServer', x=1673,72, y=65,00, z=-1179,53], wc['Sheep'/534, l='MpServer', x=1674,47, y=73,00, z=-1166,25], wc['Sheep'/561, l='MpServer', x=1690,81, y=71,00, z=-1211,38], wc['Sheep'/562, l='MpServer', x=1669,72, y=70,00, z=-1213,59], wc['Sheep'/563, l='MpServer', x=1681,44, y=71,00, z=-1207,31], wc['Sheep'/564, l='MpServer', x=1692,47, y=72,00, z=-1190,66], wc['Sheep'/565, l='MpServer', x=1687,34, y=72,00, z=-1199,69], wc['Sheep'/566, l='MpServer', x=1694,09, y=68,43, z=-1169,81], wc['Sheep'/567, l='MpServer', x=1692,28, y=64,00, z=-1183,53], wc['Sheep'/569, l='MpServer', x=1692,47, y=65,00, z=-1119,78], wc['Sheep'/586, l='MpServer', x=1701,72, y=69,00, z=-1193,50], ze['Skeleton'/62561, l='MpServer', x=1554,50, y=47,00, z=-1109,50], rw['Experience Orb'/34411, l='MpServer', x=1570,50, y=70,00, z=-1172,66], rw['Experience Orb'/34412, l='MpServer', x=1569,19, y=70,00, z=-1169,66], rw['Experience Orb'/34413, l='MpServer', x=1566,97, y=69,00, z=-1171,25], ze['Skeleton'/42101, l='MpServer', x=1544,50, y=70,00, z=-1184,50], vv['Chicken'/21622, l='MpServer', x=1604,50, y=69,50, z=-1114,22], yq['Creeper'/48759, l='MpServer', x=1685,72, y=72,00, z=-1200,56], ze['Skeleton'/62584, l='MpServer', x=1602,50, y=69,00, z=-1197,50], zi['Zombie'/62587, l='MpServer', x=1604,47, y=69,00, z=-1200,22], zg['Spider'/56459, l='MpServer', x=1544,97, y=69,00, z=-1197,63], yq['Creeper'/56476, l='MpServer', x=1675,50, y=62,00, z=-1139,50], yq['Creeper'/52897, l='MpServer', x=1681,50, y=69,00, z=-1224,50], yr['Enderman'/11439, l='MpServer', x=1682,69, y=25,00, z=-1185,56], yc['item.item.arrow'/33985, l='MpServer', x=1572,41, y=70,00, z=-1165,19], yc['item.item.bone'/33986, l='MpServer', x=1571,94, y=70,00, z=-1165,13], vs['Bat'/34504, l='MpServer', x=1691,63, y=13,16, z=-1139,19], zi['Zombie'/49882, l='MpServer', x=1551,69, y=69,00, z=-1163,63], zi['Zombie'/49894, l='MpServer', x=1617,75, y=70,00, z=-1194,53], yq['Creeper'/49897, l='MpServer', x=1685,50, y=26,00, z=-1185,50], zi['Zombie'/46316, l='MpServer', x=1657,50, y=12,00, z=-1081,50], zm['Villager'/255, l='MpServer', x=1632,41, y=73,00, z=-1151,28], rw['Experience Orb'/34047, l='MpServer', x=1570,50, y=70,00, z=-1164,75], zm['Villager'/256, l='MpServer', x=1634,50, y=73,00, z=-1150,50], rw['Experience Orb'/34048, l='MpServer', x=1569,84, y=70,00, z=-1165,56], rw['Experience Orb'/34050, l='MpServer', x=1568,28, y=70,00, z=-1165,38], wc['Sheep'/259, l='MpServer', x=1601,78, y=68,00, z=-1186,31], zm['Villager'/260, l='MpServer', x=1634,31, y=70,00, z=-1150,50], zm['Villager'/261, l='MpServer', x=1634,47, y=70,00, z=-1152,19], zm['Villager'/262, l='MpServer', x=1634,69, y=70,00, z=-1152,78], zi['Zombie'/34566, l='MpServer', x=1549,19, y=73,00, z=-1214,59], zm['Villager'/263, l='MpServer', x=1634,69, y=70,00, z=-1151,16], wf['Iron Golem'/264, l='MpServer', x=1628,00, y=70,00, z=-1150,57], zm['Villager'/266, l='MpServer', x=1632,50, y=70,00, z=-1150,50], zm['Villager'/267, l='MpServer', x=1632,72, y=70,00, z=-1149,66], zm['Villager'/268, l='MpServer', x=1632,41, y=70,00, z=-1152,84], zm['Villager'/269, l='MpServer', x=1636,81, y=70,00, z=-1151,63], zm['Villager'/270, l='MpServer', x=1634,44, y=73,00, z=-1151,75], zm['Villager'/271, l='MpServer', x=1632,28, y=70,00, z=-1151,91], we['Squid'/57615, l='MpServer', x=1615,41, y=60,06, z=-1094,84], zm['Villager'/272, l='MpServer', x=1633,41, y=70,00, z=-1144,72], we['Squid'/57616, l='MpServer', x=1611,69, y=61,38, z=-1090,50], zm['Villager'/273, l='MpServer', x=1633,59, y=70,00, z=-1152,72], we['Squid'/57617, l='MpServer', x=1608,38, y=61,00, z=-1092,84], zm['Villager'/274, l='MpServer', x=1633,13, y=70,00, z=-1151,31], zm['Villager'/275, l='MpServer', x=1634,03, y=70,00, z=-1151,41], zm['Villager'/276, l='MpServer', x=1634,47, y=70,00, z=-1153,53], zm['Villager'/277, l='MpServer', x=1639,22, y=70,00, z=-1142,78], zm['Villager'/278, l='MpServer', x=1632,94, y=70,00, z=-1152,19], zm['Villager'/279, l='MpServer', x=1650,19, y=70,00, z=-1152,53], zi['Zombie'/56087, l='MpServer', x=1622,50, y=70,00, z=-1140,65], zi['Zombie'/56088, l='MpServer', x=1623,05, y=70,00, z=-1136,43], wc['Sheep'/282, l='MpServer', x=1678,25, y=72,00, z=-1206,59], zi['Zombie'/55596, l='MpServer', x=1669,21, y=72,00, z=-1157,40], yq['Creeper'/10040, l='MpServer', x=1599,50, y=70,00, z=-1104,50], zi['Zombie'/33600, l='MpServer', x=1547,34, y=69,00, z=-1164,22], yq['Creeper'/62786, l='MpServer', x=1670,50, y=25,00, z=-1173,50], ze['Skeleton'/33605, l='MpServer', x=1615,50, y=70,00, z=-1227,50], ye['container.minecart'/327, l='MpServer', x=1547,50, y=28,06, z=-1150,53], wc['Sheep'/332, l='MpServer', x=1559,28, y=77,00, z=-1217,53], yq['Creeper'/31052, l='MpServer', x=1571,50, y=70,00, z=-1177,50], wc['Sheep'/334, l='MpServer', x=1556,47, y=80,00, z=-1226,28], yq['Creeper'/31055, l='MpServer', x=1573,75, y=70,00, z=-1175,53], wc['Sheep'/335, l='MpServer', x=1554,44, y=80,00, z=-1228,56], wi['Horse'/340, l='MpServer', x=1560,09, y=72,00, z=-1155,00], ze['Skeleton'/31060, l='MpServer', x=1570,66, y=70,00, z=-1173,84], wa['Pig'/341, l='MpServer', x=1565,41, y=64,00, z=-1106,78], wa['Pig'/342, l='MpServer', x=1564,06, y=64,00, z=-1102,09], wa['Pig'/343, l='MpServer', x=1569,28, y=64,00, z=-1102,09], wa['Pig'/344, l='MpServer', x=1570,28, y=64,00, z=-1103,16], bmp['Wyrdfell'/281, l='MpServer', x=1622,50, y=70,00, z=-1151,94], wc['Sheep'/353, l='MpServer', x=1567,75, y=72,00, z=-1208,59], ye['container.minecart'/358, l='MpServer', x=1580,50, y=34,06, z=-1170,50], wi['Horse'/361, l='MpServer', x=1575,00, y=72,00, z=-1157,97], wi['Horse'/362, l='MpServer', x=1570,97, y=72,00, z=-1157,84], xq['entity.ItemFrame.name'/363, l='MpServer', x=1578,03, y=76,50, z=-1153,50], wi['Horse'/364, l='MpServer', x=1575,00, y=72,00, z=-1149,72], wi['Horse'/365, l='MpServer', x=1571,00, y=72,00, z=-1149,84], xo['Armor Stand'/366, l='MpServer', x=1575,50, y=64,03, z=-1119,50], zg['Spider'/10094, l='MpServer', x=1586,50, y=67,00, z=-1093,50], vw['Cow'/367, l='MpServer', x=1582,88, y=64,00, z=-1103,16], wa['Pig'/368, l='MpServer', x=1571,22, y=64,00, z=-1109,44], vs['Bat'/61296, l='MpServer', x=1672,16, y=18,10, z=-1089,56], vw['Cow'/369, l='MpServer', x=1576,28, y=64,00, z=-1109,19], vw['Cow'/370, l='MpServer', x=1582,78, y=64,00, z=-1109,38], vw['Cow'/371, l='MpServer', x=1583,91, y=64,00, z=-1109,94], vw['Cow'/372, l='MpServer', x=1578,91, y=64,00, z=-1102,63], vw['Cow'/373, l='MpServer', x=1583,91, y=64,00, z=-1104,13], wa['Pig'/374, l='MpServer', x=1571,91, y=64,00, z=-1102,09], yq['Creeper'/62326, l='MpServer', x=1692,50, y=30,00, z=-1176,50], wa['Pig'/375, l='MpServer', x=1569,50, y=64,00, z=-1104,22], yq['Creeper'/62327, l='MpServer', x=1692,50, y=30,00, z=-1176,50], vw['Cow'/376, l='MpServer', x=1583,66, y=64,00, z=-1105,81], vw['Cow'/377, l='MpServer', x=1576,06, y=64,00, z=-1102,09], wa['Pig'/378, l='MpServer', x=1570,91, y=64,00, z=-1102,09], vw['Cow'/379, l='MpServer', x=1582,53, y=64,00, z=-1102,09], wa['Pig'/380, l='MpServer', x=1571,38, y=64,00, z=-1103,72], vw['Cow'/381, l='MpServer', x=1577,91, y=64,00, z=-1103,44], vw['Cow'/382, l='MpServer', x=1576,66, y=64,00, z=-1103,03], vs['Bat'/31106, l='MpServer', x=1609,41, y=28,10, z=-1086,25], xs['Painting'/411, l='MpServer', x=1591,03, y=78,50, z=-1140,00], wc['Sheep'/393, l='MpServer', x=1585,72, y=75,00, z=-1228,53], xs['Painting'/418, l='MpServer', x=1594,00, y=69,50, z=-1147,03], wc['Sheep'/397, l='MpServer', x=1588,56, y=69,00, z=-1201,22], xq['entity.ItemFrame.name'/399, l='MpServer', x=1597,03, y=67,50, z=-1153,50], xq['entity.ItemFrame.name'/400, l='MpServer', x=1598,50, y=67,50, z=-1153,97], xs['Painting'/420, l='MpServer', x=1598,00, y=74,50, z=-1135,03], xq['entity.ItemFrame.name'/401, l='MpServer', x=1598,50, y=68,50, z=-1153,97], xq['entity.ItemFrame.name'/402, l='MpServer', x=1598,50, y=69,50, z=-1153,97], xq['entity.ItemFrame.name'/403, l='MpServer', x=1598,50, y=70,50, z=-1153,97], xq['entity.ItemFrame.name'/404, l='MpServer', x=1598,97, y=69,50, z=-1152,50], xq['entity.ItemFrame.name'/405, l='MpServer', x=1598,97, y=68,50, z=-1152,50], xq['entity.ItemFrame.name'/406, l='MpServer', x=1598,97, y=67,50, z=-1152,50], xq['entity.ItemFrame.name'/407, l='MpServer', x=1597,03, y=68,50, z=-1153,50], xq['entity.ItemFrame.name'/408, l='MpServer', x=1597,03, y=69,50, z=-1153,50], xq['entity.ItemFrame.name'/409, l='MpServer', x=1597,03, y=70,50, z=-1153,50], xq['entity.ItemFrame.name'/410, l='MpServer', x=1598,97, y=70,50, z=-1152,50], xs['Painting'/411, l='MpServer', x=1591,03, y=78,50, z=-1140,00], xq['entity.ItemFrame.name'/412, l='MpServer', x=1599,97, y=74,50, z=-1143,50], xo['Armor Stand'/413, l='MpServer', x=1592,50, y=76,00, z=-1137,50], xq['entity.ItemFrame.name'/414, l='MpServer', x=1599,97, y=73,50, z=-1143,50], xq['entity.ItemFrame.name'/415, l='MpServer', x=1596,50, y=74,50, z=-1144,97], xq['entity.ItemFrame.name'/416, l='MpServer', x=1599,97, y=72,50, z=-1143,50], xo['Armor Stand'/417, l='MpServer', x=1593,50, y=67,00, z=-1151,50], xs['Painting'/418, l='MpServer', x=1594,00, y=69,50, z=-1147,03], xq['entity.ItemFrame.name'/419, l='MpServer', x=1593,50, y=69,50, z=-1150,97], xs['Painting'/420, l='MpServer', x=1598,00, y=74,50, z=-1135,03], yq['Creeper'/51108, l='MpServer', x=1590,50, y=71,00, z=-1229,50], zg['Spider'/34725, l='MpServer', x=1688,50, y=80,00, z=-1079,50], wc['Sheep'/421, l='MpServer', x=1586,50, y=65,00, z=-1074,78], zi['Zombie'/21416, l='MpServer', x=1619,50, y=16,00, z=-1079,50], yq['Creeper'/62889, l='MpServer', x=1668,50, y=32,00, z=-1174,50], wc['Sheep'/429, l='MpServer', x=1605,28, y=69,00, z=-1206,78], wc['Sheep'/430, l='MpServer', x=1609,56, y=69,00, z=-1199,28], yq['Creeper'/34735, l='MpServer', x=1615,50, y=69,00, z=-1219,50], we['Squid'/432, l='MpServer', x=1611,21, y=48,60, z=-1134,03], yq['Creeper'/34736, l='MpServer', x=1612,50, y=69,00, z=-1222,50], we['Squid'/434, l='MpServer', x=1612,47, y=46,81, z=-1131,41], vv['Chicken'/435, l='MpServer', x=1604,19, y=71,06, z=-1111,78], vv['Chicken'/436, l='MpServer', x=1604,19, y=71,06, z=-1112,56], vv['Chicken'/437, l='MpServer', x=1604,78, y=71,06, z=-1111,69], vv['Chicken'/438, l='MpServer', x=1604,78, y=71,06, z=-1112,56], vv['Chicken'/439, l='MpServer', x=1604,78, y=71,06, z=-1112,13], vv['Chicken'/440, l='MpServer', x=1604,78, y=71,06, z=-1111,22], vv['Chicken'/441, l='MpServer', x=1604,19, y=71,06, z=-1112,16], vv['Chicken'/442, l='MpServer', x=1604,78, y=71,06, z=-1113,31], vv['Chicken'/443, l='MpServer', x=1604,28, y=71,06, z=-1113,00], vv['Chicken'/444, l='MpServer', x=1604,19, y=71,06, z=-1111,22], vv['Chicken'/445, l='MpServer', x=1604,19, y=71,06, z=-1113,81], vv['Chicken'/446, l='MpServer', x=1604,50, y=69,50, z=-1114,22], vv['Chicken'/447, l='MpServer', x=1604,50, y=69,50, z=-1114,22], vv['Chicken'/448, l='MpServer', x=1604,50, y=69,50, z=-1114,22], wc['Sheep'/449, l='MpServer', x=1600,47, y=56,00, z=-1088,25], wc['Sheep'/461, l='MpServer', x=1624,53, y=68,00, z=-1219,56], wc['Sheep'/462, l='MpServer', x=1628,50, y=67,23, z=-1209,47], wc['Sheep'/463, l='MpServer', x=1626,44, y=67,33, z=-1209,47], wc['Sheep'/464, l='MpServer', x=1621,31, y=70,00, z=-1215,25], yc['item.item.seeds'/15824, l='MpServer', x=1618,56, y=69,00, z=-1155,81], yc['item.item.string'/465, l='MpServer', x=1628,44, y=70,00, z=-1155,69], wh['Wolf'/467, l='MpServer', x=1613,53, y=66,00, z=-1140,53], wh['Wolf'/468, l='MpServer', x=1610,56, y=69,00, z=-1140,53], zm['Villager'/469, l='MpServer', x=1632,47, y=70,00, z=-1153,53], yq['Creeper'/21462, l='MpServer', x=1549,50, y=56,00, z=-1221,50], vs['Bat'/40406, l='MpServer', x=1655,81, y=12,83, z=-1077,21], yq['Creeper'/53207, l='MpServer', x=1652,19, y=70,00, z=-1180,50], rw['Experience Orb'/479, l='MpServer', x=1634,97, y=68,00, z=-1270,59], rw['Experience Orb'/480, l='MpServer', x=1634,53, y=68,00, z=-1270,66], wc['Sheep'/510, l='MpServer', x=1659,47, y=70,00, z=-1212,75]]
Retry entities: 0 total; []
Server brand: vanilla
Server type: Integrated singleplayer server
Stacktrace:
at bkq.a(SourceFile:365)
at bcc.b(SourceFile:2503)
at bcc.a(SourceFile:399)
at net.minecraft.client.main.Main.main(SourceFile:122)

– System Details –
Details:
Minecraft Version: 16w03a
Operating System: Windows 7 (amd64) version 6.1
Java Version: 1.8.0_25, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 1837000328 bytes (1751 MB) / 2090336256 bytes (1993 MB) up to 2090336256 bytes (1993 MB)
JVM Flags: 3 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx2048M -Xms2048M
IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
Launched Version: 16w03a
LWJGL: 2.9.4
OpenGL: ATI Mobility Radeon HD 6370 GL version 4.0.9910 Compatibility Profile Context, ATI Technologies Inc.
GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.
Shaders are available because OpenGL 2.1 is supported.
VBOs are available because OpenGL 1.5 is supported.

Using VBOs: Yes
Is Modded: Probably not. Jar signature remains and client brand is untouched.
Type: Client (map_client.txt)
Resource Packs:
Current Language: English (US)
Profiler Position: N/A (disabled)
CPU: 4x Intel(R) Core(TM) i3 CPU M 380 @ 2.53GHz

must likely duplicate of MC-94438

... caused by used-up memory:

Memory: 1837000328 bytes (1751 MB) / 2090336256 bytes (1993 MB) up to 2090336256 bytes (1993 MB)

_Edit:
No, didn't see {{ -Xmx2048M -Xms2048M}} in the first place, but still a duplicate.