diff --git a/src/calibre/library/caches.py b/src/calibre/library/caches.py
index 7d8a8624a9..a9ef6a4281 100644
--- a/src/calibre/library/caches.py
+++ b/src/calibre/library/caches.py
@@ -67,6 +67,11 @@ class MetadataBackup(Thread): # {{{
                     prints('Failed to get backup metadata for id:', id_, 'again, giving up')
                     traceback.print_exc()
                     continue
+
+            # Give the GUI thread a chance to do something. Python threads don't
+            # have priorities, so this thread would naturally keep the processor
+            # until some scheduling event happens. The sleep makes such an event
+            time.sleep(0.010)
             try:
                 print 'now do metadata'
                 raw = metadata_to_opf(mi)
@@ -75,6 +80,7 @@ class MetadataBackup(Thread): # {{{
                 traceback.print_exc()
                 continue
 
+            time.sleep(0.010) # Give the GUI thread a chance to do something
             try:
                 self.do_write(path, raw)
             except:
@@ -87,6 +93,7 @@ class MetadataBackup(Thread): # {{{
                             'again, giving up')
                     continue
 
+            time.sleep(0.010) # Give the GUI thread a chance to do something
             try:
                 self.clear_dirtied([id_])
             except: