Keeps Crashing!!!

The game will start to load, say "not responding" in the load bar, allow me to select a world but as soon as the world loads, it crashes with the following problems listed:
06:44:50 qn Invalid statistic in C:\Users\Teresa\AppData\Roaming\.minecraft\saves\New Sea\stats\abceaecb-633b-4b7a-b778-2bcc14e8d689.json: Don't know what achievement.buildWorkBench is
06:44:50 qn Invalid statistic in C:\Users\Teresa\AppData\Roaming\.minecraft\saves\New Sea\stats\abceaecb-633b-4b7a-b778-2bcc14e8d689.json: Don't know what achievement.killCow is
06:44:50 qn Invalid statistic in C:\Users\Teresa\AppData\Roaming\.minecraft\saves\New Sea\stats\abceaecb-633b-4b7a-b778-2bcc14e8d689.json: Don't know what achievement.exploreAllBiomes is
06:44:50 qn Invalid statistic in C:\Users\Teresa\AppData\Roaming\.minecraft\saves\New Sea\stats\abceaecb-633b-4b7a-b778-2bcc14e8d689.json: Don't know what achievement.buildPickaxe is
06:44:50 qn Invalid statistic in C:\Users\Teresa\AppData\Roaming\.minecraft\saves\New Sea\stats\abceaecb-633b-4b7a-b778-2bcc14e8d689.json: Don't know what achievement.buildSword is
06:44:50 qn Invalid statistic in C:\Users\Teresa\AppData\Roaming\.minecraft\saves\New Sea\stats\abceaecb-633b-4b7a-b778-2bcc14e8d689.json: Don't know what achievement.mineWood is
06:44:50 qn Invalid statistic in C:\Users\Teresa\AppData\Roaming\.minecraft\saves\New Sea\stats\abceaecb-633b-4b7a-b778-2bcc14e8d689.json: Don't know what achievement.openInventory is
06:44:56 net.minecraft.server.MinecraftServer Can't keep up! Did the system time change, or is the server overloaded? Running 6450ms behind, skipping 129 tick(s)

It is infuriating. Can someone please help me?