diff --git a/src/calibre/gui2/dialogs/config.py b/src/calibre/gui2/dialogs/config.py
index c4e673c8b8..e328ce641d 100644
--- a/src/calibre/gui2/dialogs/config.py
+++ b/src/calibre/gui2/dialogs/config.py
@@ -6,7 +6,7 @@ from PyQt4.QtGui import QDialog, QMessageBox, QListWidgetItem, QIcon, \
                         QDesktopServices, QVBoxLayout, QLabel, QPlainTextEdit
 from PyQt4.QtCore import SIGNAL, QTimer, Qt, QSize, QVariant, QUrl
 
-from calibre import islinux
+from calibre.constants import islinux, iswindows
 from calibre.gui2.dialogs.config_ui import Ui_Dialog
 from calibre.gui2 import qstring_to_unicode, choose_dir, error_dialog, config, \
                          warning_dialog, ALL_COLUMNS
@@ -116,6 +116,10 @@ class ConfigDialog(QDialog, Ui_Dialog):
         self.systray_icon.setChecked(config['systray_icon'])
         self.sync_news.setChecked(config['upload_news_to_device'])
         self.delete_news.setChecked(config['delete_news_from_library_on_upload'])
+        p = {'normal':0, 'high':1, 'low':2}[prefs['worker_process_priority']]
+        self.priority.setCurrentIndex(p)
+        self.priority.setVisible(iswindows)
+        self.priority_label.setVisible(iswindows)
     
     def up_column(self):
         idx = self.columns.currentRow()
@@ -212,6 +216,8 @@ class ConfigDialog(QDialog, Ui_Dialog):
         config['confirm_delete'] =  bool(self.confirm_delete.isChecked())
         pattern = self.filename_pattern.commit()
         prefs['filename_pattern'] = pattern
+        p = {0:'normal', 1:'high', 2:'low'}[self.priority.currentIndex()]
+        prefs['worker_process_priority'] = p
         prefs['read_file_metadata'] = bool(self.pdf_metadata.isChecked())
         config['save_to_disk_single_format'] = BOOK_EXTENSIONS[self.single_format.currentIndex()]
         config['cover_flow_queue_length'] = self.cover_browse.value()
diff --git a/src/calibre/gui2/dialogs/config.ui b/src/calibre/gui2/dialogs/config.ui
index 776855fa7c..55c52a5fd3 100644
--- a/src/calibre/gui2/dialogs/config.ui
+++ b/src/calibre/gui2/dialogs/config.ui
@@ -231,6 +231,35 @@
              </property>
             </widget>
            </item>
+           <item row="4" column="1" >
+            <widget class="QComboBox" name="priority" >
+             <item>
+              <property name="text" >
+               <string>Normal</string>
+              </property>
+             </item>
+             <item>
+              <property name="text" >
+               <string>High</string>
+              </property>
+             </item>
+             <item>
+              <property name="text" >
+               <string>Low</string>
+              </property>
+             </item>
+            </widget>
+           </item>
+           <item row="4" column="0" >
+            <widget class="QLabel" name="priority_label" >
+             <property name="text" >
+              <string>Job &amp;priority:</string>
+             </property>
+             <property name="buddy" >
+              <cstring>priority</cstring>
+             </property>
+            </widget>
+           </item>
           </layout>
          </item>
          <item>
diff --git a/src/calibre/parallel.py b/src/calibre/parallel.py
index 0b84568a9f..fbc9ba3d9b 100644
--- a/src/calibre/parallel.py
+++ b/src/calibre/parallel.py
@@ -32,6 +32,7 @@ from math import ceil
 
 from calibre.ptempfile import PersistentTemporaryFile
 from calibre import iswindows, detect_ncpus, isosx
+from calibre.utils.config import prefs
 
 DEBUG = False
 
@@ -223,6 +224,8 @@ class WorkerMother(object):
         return child
 
     def spawn_free_spirit_windows(self, arg, type='free_spirit'):
+        priority = {'high':win32process.HIGH_PRIORITY_CLASS, 'normal':win32process.NORMAL_PRIORITY_CLASS,
+                    'low':win32process.IDLE_PRIORITY_CLASS}[prefs['worker_process_priority']]
         fd, name = tempfile.mkstemp('.log', 'calibre_'+type+'_')
         handle = msvcrt.get_osfhandle(fd)
         si = win32process.STARTUPINFO()
@@ -236,7 +239,7 @@ class WorkerMother(object):
             None,    # processAttributes
             None,    # threadAttributes
             1,       # bInheritHandles
-            win32process.CREATE_NO_WINDOW, # Dont want ugly console popping up
+            win32process.CREATE_NO_WINDOW|priority, # Dont want ugly console popping up
             self.get_env(), # New environment
             None,    # Current directory
             si
diff --git a/src/calibre/utils/config.py b/src/calibre/utils/config.py
index 1327fd415c..59db9f38e1 100644
--- a/src/calibre/utils/config.py
+++ b/src/calibre/utils/config.py
@@ -536,6 +536,8 @@ def _prefs():
               help=_('The default output format for ebook conversions.'))
     c.add_opt('read_file_metadata', default=True,
               help=_('Read metadata from files'))
+    c.add_opt('worker_process_priority', default='normal', 
+              help=_('The priority of worker processes'))
     
     c.add_opt('migrated', default=False, help='For Internal use. Don\'t modify.')
     return c