diff --git a/freqtrade/misc.py b/freqtrade/misc.py
index 49d33d46f..2d2c7513a 100644
--- a/freqtrade/misc.py
+++ b/freqtrade/misc.py
@@ -10,7 +10,8 @@ from typing import Any, Dict, Iterator, List, Mapping, Union
 from typing.io import IO
 from urllib.parse import urlparse
 
-import pandas
+import orjson
+import pandas as pd
 import rapidjson
 
 from freqtrade.constants import DECIMAL_PER_COIN_FALLBACK, DECIMALS_PER_COIN
@@ -256,29 +257,37 @@ def parse_db_uri_for_logging(uri: str):
     return parsed_db_uri.geturl().replace(f':{pwd}@', ':*****@')
 
 
-def dataframe_to_json(dataframe: pandas.DataFrame) -> str:
+def dataframe_to_json(dataframe: pd.DataFrame) -> str:
     """
     Serialize a DataFrame for transmission over the wire using JSON
     :param dataframe: A pandas DataFrame
     :returns: A JSON string of the pandas DataFrame
     """
-    return dataframe.to_json(orient='split')
+    # https://github.com/pandas-dev/pandas/issues/24889
+    # https://github.com/pandas-dev/pandas/issues/40443
+    # We need to convert to a dict to avoid mem leak
+    def default(z):
+        if isinstance(z, pd.Timestamp):
+            return z.timestamp() * 1e3
+        raise TypeError
+
+    return str(orjson.dumps(dataframe.to_dict(orient='split'), default=default), 'utf-8')
 
 
-def json_to_dataframe(data: str) -> pandas.DataFrame:
+def json_to_dataframe(data: str) -> pd.DataFrame:
     """
     Deserialize JSON into a DataFrame
     :param data: A JSON string
     :returns: A pandas DataFrame from the JSON string
     """
-    dataframe = pandas.read_json(data, orient='split')
+    dataframe = pd.read_json(data, orient='split')
     if 'date' in dataframe.columns:
-        dataframe['date'] = pandas.to_datetime(dataframe['date'], unit='ms', utc=True)
+        dataframe['date'] = pd.to_datetime(dataframe['date'], unit='ms', utc=True)
 
     return dataframe
 
 
-def remove_entry_exit_signals(dataframe: pandas.DataFrame):
+def remove_entry_exit_signals(dataframe: pd.DataFrame):
     """
     Remove Entry and Exit signals from a DataFrame
 
diff --git a/freqtrade/rpc/api_server/ws/channel.py b/freqtrade/rpc/api_server/ws/channel.py
index 88b4db9ba..4eef738d4 100644
--- a/freqtrade/rpc/api_server/ws/channel.py
+++ b/freqtrade/rpc/api_server/ws/channel.py
@@ -77,21 +77,24 @@ class WebSocketChannel:
         # until self.drain_timeout for the relay to drain the outgoing queue
         # We can't use asyncio.wait_for here because the queue may have been created with a
         # different eventloop
-        start = time.time()
-        while self.queue.full():
-            await asyncio.sleep(1)
-            if (time.time() - start) > self.drain_timeout:
+        if not self.is_closed():
+            start = time.time()
+            while self.queue.full():
+                await asyncio.sleep(1)
+                if (time.time() - start) > self.drain_timeout:
+                    return False
+
+            # If for some reason the queue is still full, just return False
+            try:
+                self.queue.put_nowait(data)
+            except asyncio.QueueFull:
                 return False
 
-        # If for some reason the queue is still full, just return False
-        try:
-            self.queue.put_nowait(data)
-        except asyncio.QueueFull:
+            # If we got here everything is ok
+            return True
+        else:
             return False
 
-        # If we got here everything is ok
-        return True
-
     async def recv(self):
         """
         Receive data on the wrapped websocket
@@ -109,14 +112,14 @@ class WebSocketChannel:
         Close the WebSocketChannel
         """
 
+        self._closed.set()
+        self._relay_task.cancel()
+
         try:
             await self.raw_websocket.close()
         except Exception:
             pass
 
-        self._closed.set()
-        self._relay_task.cancel()
-
     def is_closed(self) -> bool:
         """
         Closed flag