diff --git a/visidata/vdtui.py b/visidata/vdtui.py
index <HASH>..<HASH> 100755
--- a/visidata/vdtui.py
+++ b/visidata/vdtui.py
@@ -494,6 +494,7 @@ class VisiData:
     def sync(self, expectedThreads=0):
         'Wait for all but expectedThreads async threads to finish.'
         while len(self.unfinishedThreads) > expectedThreads:
+            time.sleep(.3)
             self.checkForFinishedThreads()
 
     def refresh(self):
[vdtui] sync() should sleep() in spin loop