Loading 200-300 chunks per second crashes server (frozen tick)

[LysergikProductions]

https://paste.shockbyte.com/wepalizekewezubaqihe

In this instance where the frozen-tick did not lead to a crash you can see the following (and a chunk-lighting) thread are waiting for new data to process and cannot continue.
https://pastebin.com/TcCfc7Ds

When the thread dies completely, here is the stack:

28.04 19:58:06 [Server] FATAL Failed to schedule unload callback for chunk [-246, -500]
28.04 19:58:06 [Server] INFO java.util.concurrent.CompletionException: java.lang.ThreadDeath
28.04 19:58:06 [Server] INFO at java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:273) ~[?:1.8.0_201]
28.04 19:58:06 [Server] INFO at java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:280) ~[?:1.8.0_201]
28.04 19:58:06 [Server] INFO at java.util.concurrent.CompletableFuture.uniCompose(CompletableFuture.java:961) ~[?:1.8.0_201]
28.04 19:58:06 [Server] INFO at java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:926) ~[?:1.8.0_201]
28.04 19:58:06 [Server] INFO at java.util.concurrent.CompletableFuture$Completion.run(CompletableFuture.java:442) ~[?:1.8.0_201]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.IAsyncTaskHandler.executeTask(IAsyncTaskHandler.java:136) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.ChunkProviderServer$a.executeTask(ChunkProviderServer.java:1027) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.IAsyncTaskHandler.executeNext(IAsyncTaskHandler.java:109) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.ChunkProviderServer$a.executeNext(ChunkProviderServer.java:1074) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.IAsyncTaskHandler.awaitTasks(IAsyncTaskHandler.java:119) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.ChunkProviderServer.getChunkAt(ChunkProviderServer.java:536) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.World.getType(World.java:736) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.VoxelShapeSpliterator.a(VoxelShapeSpliterator.java:87) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.VoxelShapeSpliterator.tryAdvance(VoxelShapeSpliterator.java:64) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at java.util.stream.Streams$ConcatSpliterator.tryAdvance(Streams.java:731) ~[?:1.8.0_201]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.StreamAccumulator$1.tryAdvance(SourceFile:31) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at java.util.Spliterators$1Adapter.hasNext(Spliterators.java:681) ~[?:1.8.0_201]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.VoxelShapes.a(VoxelShapes.java:190) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.Entity.a(Entity.java:969) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.Entity.a(Entity.java:957) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.Entity.g(Entity.java:919) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.Entity.move(Entity.java:714) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.PlayerConnection.a(PlayerConnection.java:1347) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.PacketPlayInFlying.a(SourceFile:122) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.PacketPlayInFlying$PacketPlayInPosition.a(SourceFile:56) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.PlayerConnectionUtils.lambda$ensureMainThread$1(PlayerConnectionUtils.java:35) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.TickTask.run(SourceFile:18) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.IAsyncTaskHandler.executeTask(IAsyncTaskHandler.java:136) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.IAsyncTaskHandlerReentrant.executeTask(SourceFile:23) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.IAsyncTaskHandler.executeNext(IAsyncTaskHandler.java:109) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.MinecraftServer.bb(MinecraftServer.java:1262) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.MinecraftServer.executeNext(MinecraftServer.java:1255) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.IAsyncTaskHandler.executeAll(IAsyncTaskHandler.java:95) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.MinecraftServer.a(MinecraftServer.java:1391) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.MinecraftServer.w(MinecraftServer.java:1126) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at net.minecraft.server.v1_16_R3.MinecraftServer.lambda$a$0(MinecraftServer.java:289) ~[patched_1.16.5.jar:git-Paper-629]
28.04 19:58:06 [Server] INFO at java.lang.Thread.run(Thread.java:748) [?:1.8.0_201]
28.04 19:58:06 [Server] INFO Caused by: java.lang.ThreadDeath