diff --git a/src/scheduler/AsyncTask.php b/src/scheduler/AsyncTask.php
index 28c7a2957..c65552bf3 100644
--- a/src/scheduler/AsyncTask.php
+++ b/src/scheduler/AsyncTask.php
@@ -33,19 +33,31 @@ use function spl_object_id;
 /**
  * Class used to run async tasks in other threads.
  *
- * An AsyncTask does not have its own thread. It is queued into an AsyncPool and executed if there is an async worker
- * with no AsyncTask running. Therefore, an AsyncTask SHOULD NOT execute for more than a few seconds. For tasks that
- * run for a long time or infinitely, start another thread instead.
+ * An AsyncTask is run by a thread pool of reusable threads, and doesn't have its own dedicated thread. A thread is
+ * usually chosen from the pool at random to run the task (though a specific thread in the pool may be selected
+ * manually, if needed).
+ * Reusing threads this way has a much lower performance cost than starting an entirely new thread for every operation.
+ * AsyncTasks are therefore suitable for brief CPU-bound tasks, such as world generation, compression/decompression of
+ * data, etc.
+ *
+ * AsyncTask SHOULD NOT be used for I/O-bound tasks, such as network I/O, file I/O, database I/O, etc. The server's
+ * central AsyncPool is used for things like compressing network packets for sending, so using AsyncTask for I/O will
+ * slow the whole server down, stall chunk loading, etc.
+ *
+ * An AsyncTask SHOULD NOT run for more than a few seconds. For tasks that run for a long time or indefinitely, create
+ * a dedicated thread instead.
+ *
+ * The Server instance is not accessible inside {@link AsyncTask::onRun()}. It can only be accessed in the main server
+ * thread, e.g. during {@link AsyncTask::onCompletion()} or {@link AsyncTask::onProgressUpdate()}. This means that
+ * whatever you do in onRun() must be able to work without the Server instance.
  *
  * WARNING: Any non-Threaded objects WILL BE SERIALIZED when assigned to members of AsyncTasks or other Threaded object.
  * If later accessed from said Threaded object, you will be operating on a COPY OF THE OBJECT, NOT THE ORIGINAL OBJECT.
  * If you want to store non-serializable objects to access when the task completes, store them using
  * {@link AsyncTask::storeLocal}.
  *
- * WARNING: As of pthreads v3.1.6, arrays are converted to Volatile objects when assigned as members of Threaded objects.
+ * WARNING: Arrays are converted to Volatile objects when assigned as members of Threaded objects.
  * Keep this in mind when using arrays stored as members of your AsyncTask.
- *
- * WARNING: Do not call PocketMine-MP API methods from other Threads!!
  */
 abstract class AsyncTask extends \Threaded{
 	/**