diff --git a/src/Jobs/Handler/Print.hs b/src/Jobs/Handler/Print.hs
index 4c97d3f0d..cb16a2907 100644
--- a/src/Jobs/Handler/Print.hs
+++ b/src/Jobs/Handler/Print.hs
@@ -14,7 +14,7 @@ import Jobs.Queue
 
 -- import Jobs.Handler.Intervals.Utils
 import qualified Data.Text as Text
-import UnliftIO.Concurrent (threadDelay)
+-- import UnliftIO.Concurrent (threadDelay)
 
 -- import           Database.Persist.Sql (deleteWhereCount)
 -- import           Database.Esqueleto.Experimental ((:&)(..))
@@ -25,15 +25,15 @@ import UnliftIO.Concurrent (threadDelay)
 
 
 jobPrintAckChunkSize :: Int 
-jobPrintAckChunkSize = 32
+jobPrintAckChunkSize = 64
 
 -- needed, since JobPrintAck cannot requeue itself due to JobNoQueueSame (and having no parameters)
 dispatchJobPrintAckAgain :: JobHandler UniWorX
 dispatchJobPrintAckAgain = JobHandlerException act
   where 
-    act = do 
-      liftIO $ threadDelay 3e6 -- wait 3s before continuing
-      void $ queueJob JobPrintAck
+    act = void $ queueJob JobPrintAck
+      -- liftIO $ threadDelay 3e6 -- wait 3s before continuing UPDATE: no wait needed
+      
 
 dispatchJobPrintAck :: JobHandler UniWorX
 dispatchJobPrintAck = JobHandlerException act
diff --git a/src/Model/Migration/Definitions.hs b/src/Model/Migration/Definitions.hs
index cbb5c548b..57dff6166 100644
--- a/src/Model/Migration/Definitions.hs
+++ b/src/Model/Migration/Definitions.hs
@@ -113,7 +113,7 @@ derivePersistFieldPathPiece ''ManualMigration
 
 migrateManual :: Migration
 migrateManual = do
-  mapM_ (uncurry addIndex)
+  mapM_ (uncurry addIndex) -- NOTE: Indices are automatically created for primary keys and unique columns; manually create them frequent filter conditions that small results for speed up
     [ ("material_file_content",               "CREATE INDEX material_file_content ON material_file (content)"                            )
     , ("course_news_file_content",            "CREATE INDEX course_news_file_content ON course_news_file (content)"                      )
     , ("sheet_file_content",                  "CREATE INDEX sheet_file_content ON sheet_file (content)"                                  )
@@ -132,7 +132,12 @@ migrateManual = do
     , ("study_features_relevance_cached",     "CREATE INDEX study_features_relevance_cached ON \"study_features\" (relevance_cached)")
     , ("submission_rating_by",                "CREATE INDEX submission_rating_by ON submission (rating_by) WHERE rating_by IS NOT NULL"  )
     , ("exam_corrector_user",                 "CREATE INDEX exam_corrector_user ON exam_corrector (\"user\")"                            )
-    , ("submission_rating_time",              "CREATE INDEX submission_rating_time ON submission (rating_time)"                          )
+    , ("submission_rating_time",              "CREATE INDEX submission_rating_time ON submission (rating_time)"                          )    
+    , ("qualification_user_block_quser"  ,    "CREATE INDEX qualification_user_block_quser ON qualification_user_block (qualification_user)")
+    , ("qualification_user_block_unblock",    "CREATE INDEX qualification_user_block_unblock ON qualification_user_block (unblock)")
+    , ("qualification_user_block_from"   ,    "CREATE INDEX qualification_user_block_unblock ON qualification_user_block (from)")    
+    , ("print_job_apc_ident"             ,    "CREATE INDEX print_job_apc_ident ON print_job (apc_ident)")
+    , ("user_avs_card_person_id"         ,    "CREATE INDEX user_avs_card_person_id ON user_avs_card (person_id)")    
     ]
   where
     addIndex :: Text -> Sql -> Migration