diff --git a/src/Simplex/Chat.hs b/src/Simplex/Chat.hs
index 110b4a8bfb..b758b7901b 100644
--- a/src/Simplex/Chat.hs
+++ b/src/Simplex/Chat.hs
@@ -5659,7 +5659,7 @@ batchChatMessages = mkBatch []
       let (batch, msgs_) = encodeBatch mempty 0 0 [] msgs
           batches' = batch : batches
        in maybe batches' (mkBatch batches') msgs_
-    encodeBatch :: Builder.Builder -> Int -> Int -> [SndMessage] -> NonEmpty SndMessage -> (ChatMessageBatch, Maybe (NonEmpty SndMessage))
+    encodeBatch :: Builder.Builder -> Int64 -> Int -> [SndMessage] -> NonEmpty SndMessage -> (ChatMessageBatch, Maybe (NonEmpty SndMessage))
     encodeBatch builder len cnt batchedMsgs remainingMsgs@(msg :| msgs_)
       | len' <= maxSize' =
           case L.nonEmpty msgs_ of
@@ -5671,13 +5671,13 @@ batchChatMessages = mkBatch []
         SndMessage {msgBody} = msg
         cnt' = cnt + 1
         len'
-          | cnt' == 1 = B.length msgBody -- initially len = 0
-          | cnt' == 2 = len + B.length msgBody + 2 -- for opening bracket "[" and comma ","
-          | otherwise = len + B.length msgBody + 1 -- for comma ","
+          | cnt' == 1 = LB.length msgBody -- initially len = 0
+          | cnt' == 2 = len + LB.length msgBody + 2 -- for opening bracket "[" and comma ","
+          | otherwise = len + LB.length msgBody + 1 -- for comma ","
         builder'
-          | cnt' == 1 = Builder.byteString msgBody
-          | cnt' == 2 = "[" <> builder <> "," <> Builder.byteString msgBody
-          | otherwise = builder <> "," <> Builder.byteString msgBody
+          | cnt' == 1 = Builder.lazyByteString msgBody
+          | cnt' == 2 = "[" <> builder <> "," <> Builder.lazyByteString msgBody
+          | otherwise = builder <> "," <> Builder.lazyByteString msgBody
         completeBuilder bldr
           | cnt' == 1 = bldr
           | otherwise = bldr <> "]"
@@ -5692,27 +5692,27 @@ directMessage chatMsgEvent = do
   let r = encodeChatMessage ChatMessage {chatVRange, msgId = Nothing, chatMsgEvent}
   case r of
     Left e -> throwChatError $ CEException e
-    Right encodedBody -> pure encodedBody
+    Right encodedBody -> pure . LB.toStrict $ encodedBody
 
-deliverMessage :: ChatMonad m => Connection -> CMEventTag e -> MsgBody -> MessageId -> m Int64
+deliverMessage :: ChatMonad m => Connection -> CMEventTag e -> LazyMsgBody -> MessageId -> m Int64
 deliverMessage conn cmEventTag msgBody msgId = do
   let msgFlags = MsgFlags {notification = hasNotification cmEventTag}
   deliverMessage' conn msgFlags msgBody msgId
 
-deliverMessage' :: ChatMonad m => Connection -> MsgFlags -> MsgBody -> MessageId -> m Int64
+deliverMessage' :: ChatMonad m => Connection -> MsgFlags -> LazyMsgBody -> MessageId -> m Int64
 deliverMessage' conn msgFlags msgBody msgId =
   deliverMessages [(conn, msgFlags, msgBody, msgId)] >>= \case
     [r] -> liftEither r
     rs -> throwChatError $ CEInternalError $ "deliverMessage: expected 1 result, got " <> show (length rs)
 
-deliverMessages :: ChatMonad' m => [(Connection, MsgFlags, MsgBody, MessageId)] -> m [Either ChatError Int64]
+deliverMessages :: ChatMonad' m => [(Connection, MsgFlags, LazyMsgBody, MessageId)] -> m [Either ChatError Int64]
 deliverMessages msgReqs = do
   sent <- zipWith prepareBatch msgReqs <$> withAgent' (`sendMessages` aReqs)
   withStoreBatch $ \db -> map (bindRight $ createDelivery db) sent
   where
-    aReqs = map (\(conn, msgFlags, msgBody, _msgId) -> (aConnId conn, msgFlags, msgBody)) msgReqs
+    aReqs = map (\(conn, msgFlags, msgBody, _msgId) -> (aConnId conn, msgFlags, LB.toStrict msgBody)) msgReqs
     prepareBatch req = bimap (`ChatErrorAgent` Nothing) (req,)
-    createDelivery :: DB.Connection -> ((Connection, MsgFlags, MsgBody, MessageId), AgentMsgId) -> IO (Either ChatError Int64)
+    createDelivery :: DB.Connection -> ((Connection, MsgFlags, LazyMsgBody, MessageId), AgentMsgId) -> IO (Either ChatError Int64)
     createDelivery db ((Connection {connId}, _, _, msgId), agentMsgId) =
       Right <$> createSndMsgDelivery db (SndMsgDelivery {connId, agentMsgId}) msgId
 
@@ -5807,7 +5807,7 @@ saveDirectRcvMSG conn@Connection {connId} agentMsgMeta agentAckCmdId msgBody =
     [Right (ACMsg _ ChatMessage {chatVRange, msgId = sharedMsgId_, chatMsgEvent})] -> do
       conn' <- updatePeerChatVRange conn chatVRange
       let agentMsgId = fst $ recipient agentMsgMeta
-          newMsg = NewMessage {chatMsgEvent, msgBody}
+          newMsg = NewRcvMessage {chatMsgEvent, msgBody}
           rcvMsgDelivery = RcvMsgDelivery {connId, agentMsgId, agentMsgMeta, agentAckCmdId}
       msg <- withStore $ \db -> createNewMessageAndRcvMsgDelivery db (ConnectionId connId) newMsg sharedMsgId_ rcvMsgDelivery Nothing
       pure (conn', msg)
@@ -5818,7 +5818,7 @@ saveGroupRcvMsg :: (MsgEncodingI e, ChatMonad m) => User -> GroupId -> GroupMemb
 saveGroupRcvMsg user groupId authorMember conn@Connection {connId} agentMsgMeta agentAckCmdId msgBody ChatMessage {chatVRange, msgId = sharedMsgId_, chatMsgEvent} = do
   (am', conn') <- updateMemberChatVRange authorMember conn chatVRange
   let agentMsgId = fst $ recipient agentMsgMeta
-      newMsg = NewMessage {chatMsgEvent, msgBody}
+      newMsg = NewRcvMessage {chatMsgEvent, msgBody}
       rcvMsgDelivery = RcvMsgDelivery {connId, agentMsgId, agentMsgMeta, agentAckCmdId}
       amId = Just am'.groupMemberId
   msg <-
@@ -5834,7 +5834,7 @@ saveGroupRcvMsg user groupId authorMember conn@Connection {connId} agentMsgMeta
 
 saveGroupFwdRcvMsg :: (MsgEncodingI e, ChatMonad m) => User -> GroupId -> GroupMember -> GroupMember -> MsgBody -> ChatMessage e -> m RcvMessage
 saveGroupFwdRcvMsg user groupId forwardingMember refAuthorMember msgBody ChatMessage {msgId = sharedMsgId_, chatMsgEvent} = do
-  let newMsg = NewMessage {chatMsgEvent, msgBody}
+  let newMsg = NewRcvMessage {chatMsgEvent, msgBody}
       fwdMemberId = Just $ groupMemberId' forwardingMember
       refAuthorId = Just $ groupMemberId' refAuthorMember
   withStore (\db -> createNewRcvMessage db (GroupId groupId) newMsg sharedMsgId_ refAuthorId fwdMemberId)
diff --git a/src/Simplex/Chat/Messages.hs b/src/Simplex/Chat/Messages.hs
index 08a7807dd1..cc269be2c9 100644
--- a/src/Simplex/Chat/Messages.hs
+++ b/src/Simplex/Chat/Messages.hs
@@ -22,6 +22,7 @@ import qualified Data.Aeson.Encoding as JE
 import qualified Data.Aeson.TH as JQ
 import qualified Data.Attoparsec.ByteString.Char8 as A
 import qualified Data.ByteString.Base64 as B64
+import qualified Data.ByteString.Lazy as L
 import qualified Data.ByteString.Lazy.Char8 as LB
 import Data.Char (isSpace)
 import Data.Int (Int64)
@@ -763,17 +764,25 @@ checkChatType x = case testEquality (chatTypeI @c) (chatTypeI @c') of
   Just Refl -> Right x
   Nothing -> Left "bad chat type"
 
-data NewMessage e = NewMessage
+type LazyMsgBody = L.ByteString
+
+data NewSndMessage e = NewMessage
   { chatMsgEvent :: ChatMsgEvent e,
-    msgBody :: MsgBody
+    msgBody :: LazyMsgBody
   }
   deriving (Show)
 
 data SndMessage = SndMessage
   { msgId :: MessageId,
     sharedMsgId :: SharedMsgId,
+    msgBody :: LazyMsgBody
+  }
+
+data NewRcvMessage e = NewRcvMessage
+  { chatMsgEvent :: ChatMsgEvent e,
     msgBody :: MsgBody
   }
+  deriving (Show)
 
 data RcvMessage = RcvMessage
   { msgId :: MessageId,
@@ -787,7 +796,7 @@ data RcvMessage = RcvMessage
 data PendingGroupMessage = PendingGroupMessage
   { msgId :: MessageId,
     cmEventTag :: ACMEventTag,
-    msgBody :: MsgBody,
+    msgBody :: LazyMsgBody,
     introId_ :: Maybe Int64
   }
 
diff --git a/src/Simplex/Chat/Protocol.hs b/src/Simplex/Chat/Protocol.hs
index 863d45ce5a..c2dfd2e418 100644
--- a/src/Simplex/Chat/Protocol.hs
+++ b/src/Simplex/Chat/Protocol.hs
@@ -29,7 +29,9 @@ import qualified Data.Attoparsec.ByteString.Char8 as A
 import Data.ByteString.Char8 (ByteString)
 import qualified Data.ByteString.Char8 as B
 import Data.ByteString.Internal (c2w, w2c)
+import qualified Data.ByteString.Lazy as L
 import qualified Data.ByteString.Lazy.Char8 as LB
+import Data.Int (Int64)
 import Data.Maybe (fromMaybe)
 import Data.String
 import Data.Text (Text)
@@ -485,18 +487,18 @@ $(JQ.deriveJSON defaultJSON ''QuotedMsg)
 
 -- this limit reserves space for metadata in forwarded messages
 -- 15780 (limit used for fileChunkSize) - 161 (x.grp.msg.forward overhead) = 15619, round to 15610
-maxChatMsgSize :: Int
+maxChatMsgSize :: Int64
 maxChatMsgSize = 15610
 
-encodeChatMessage :: MsgEncodingI e => ChatMessage e -> Either String ByteString
+encodeChatMessage :: MsgEncodingI e => ChatMessage e -> Either String L.ByteString
 encodeChatMessage msg = do
   case chatToAppMessage msg of
     AMJson m -> do
-      let body = LB.toStrict $ J.encode m
-      if B.length body > maxChatMsgSize
+      let body = J.encode m
+      if LB.length body > maxChatMsgSize
         then Left "large message"
         else Right body
-    AMBinary m -> Right $ strEncode m
+    AMBinary m -> Right . LB.fromStrict $ strEncode m
 
 parseChatMessages :: ByteString -> [Either String AChatMessage]
 parseChatMessages "" = [Left "empty string"]
diff --git a/src/Simplex/Chat/Store/Messages.hs b/src/Simplex/Chat/Store/Messages.hs
index 2bae6cd28e..3e1159735e 100644
--- a/src/Simplex/Chat/Store/Messages.hs
+++ b/src/Simplex/Chat/Store/Messages.hs
@@ -160,7 +160,7 @@ deleteGroupCIs db User {userId} GroupInfo {groupId} = do
   DB.execute db "DELETE FROM chat_item_reactions WHERE group_id = ?" (Only groupId)
   DB.execute db "DELETE FROM chat_items WHERE user_id = ? AND group_id = ?" (userId, groupId)
 
-createNewSndMessage :: MsgEncodingI e => DB.Connection -> TVar ChaChaDRG -> ConnOrGroupId -> (SharedMsgId -> Either String (NewMessage e)) -> ExceptT StoreError IO SndMessage
+createNewSndMessage :: MsgEncodingI e => DB.Connection -> TVar ChaChaDRG -> ConnOrGroupId -> (SharedMsgId -> Either String (NewSndMessage e)) -> ExceptT StoreError IO SndMessage
 createNewSndMessage db gVar connOrGroupId mkMessage =
   createWithRandomId' gVar $ \sharedMsgId ->
     case mkMessage (SharedMsgId sharedMsgId) of
@@ -196,7 +196,7 @@ createSndMsgDelivery db SndMsgDelivery {connId, agentMsgId} messageId = do
     (messageId, connId, agentMsgId, currentTs, currentTs, currentTs, MDSSndAgent)
   insertedRowId db
 
-createNewMessageAndRcvMsgDelivery :: forall e. MsgEncodingI e => DB.Connection -> ConnOrGroupId -> NewMessage e -> Maybe SharedMsgId -> RcvMsgDelivery -> Maybe GroupMemberId -> ExceptT StoreError IO RcvMessage
+createNewMessageAndRcvMsgDelivery :: forall e. MsgEncodingI e => DB.Connection -> ConnOrGroupId -> NewRcvMessage e -> Maybe SharedMsgId -> RcvMsgDelivery -> Maybe GroupMemberId -> ExceptT StoreError IO RcvMessage
 createNewMessageAndRcvMsgDelivery db connOrGroupId newMessage sharedMsgId_ RcvMsgDelivery {connId, agentMsgId, agentMsgMeta, agentAckCmdId} authorGroupMemberId_ = do
   msg@RcvMessage {msgId} <- createNewRcvMessage db connOrGroupId newMessage sharedMsgId_ authorGroupMemberId_ Nothing
   liftIO $ do
@@ -211,8 +211,8 @@ createNewMessageAndRcvMsgDelivery db connOrGroupId newMessage sharedMsgId_ RcvMs
       (msgId, connId, agentMsgId, msgMetaJson agentMsgMeta, agentAckCmdId, snd $ broker agentMsgMeta, currentTs, currentTs, MDSRcvAgent)
   pure msg
 
-createNewRcvMessage :: forall e. MsgEncodingI e => DB.Connection -> ConnOrGroupId -> NewMessage e -> Maybe SharedMsgId -> Maybe GroupMemberId -> Maybe GroupMemberId -> ExceptT StoreError IO RcvMessage
-createNewRcvMessage db connOrGroupId NewMessage {chatMsgEvent, msgBody} sharedMsgId_ authorMember forwardedByMember =
+createNewRcvMessage :: forall e. MsgEncodingI e => DB.Connection -> ConnOrGroupId -> NewRcvMessage e -> Maybe SharedMsgId -> Maybe GroupMemberId -> Maybe GroupMemberId -> ExceptT StoreError IO RcvMessage
+createNewRcvMessage db connOrGroupId NewRcvMessage {chatMsgEvent, msgBody} sharedMsgId_ authorMember forwardedByMember =
   case connOrGroupId of
     ConnectionId connId -> liftIO $ insertRcvMsg (Just connId) Nothing
     GroupId groupId -> case sharedMsgId_ of
diff --git a/tests/ProtocolTests.hs b/tests/ProtocolTests.hs
index 5c6b51d3dc..925f5e6a7d 100644
--- a/tests/ProtocolTests.hs
+++ b/tests/ProtocolTests.hs
@@ -7,6 +7,7 @@ module ProtocolTests where
 
 import qualified Data.Aeson as J
 import Data.ByteString.Char8 (ByteString)
+import qualified Data.ByteString.Lazy.Char8 as LB
 import Data.Time.Clock.System (SystemTime (..), systemToUTCTime)
 import Simplex.Chat.Protocol
 import Simplex.Chat.Types
@@ -74,7 +75,7 @@ s ##== msg = do
   case r of
     Left e -> expectationFailure $ "encode error: " <> show e
     Right encodedBody ->
-      J.eitherDecodeStrict' encodedBody
+      J.eitherDecodeStrict' (LB.toStrict encodedBody)
         `shouldBe` (J.eitherDecodeStrict' s :: Either String J.Value)
 
 (##==##) :: MsgEncodingI e => ByteString -> ChatMessage e -> Expectation