diff --git a/core/src/main/groovy/com/muwire/core/MuWireSettings.groovy b/core/src/main/groovy/com/muwire/core/MuWireSettings.groovy
index 96d10be6..61d05be7 100644
--- a/core/src/main/groovy/com/muwire/core/MuWireSettings.groovy
+++ b/core/src/main/groovy/com/muwire/core/MuWireSettings.groovy
@@ -29,6 +29,7 @@ class MuWireSettings {
     CrawlerResponse crawlerResponse
     boolean shareDownloadedFiles
     boolean shareHiddenFiles
+    int hashingCores
     boolean searchComments
     boolean searchCollections
     boolean browseFiles
@@ -98,6 +99,7 @@ class MuWireSettings {
         updateType = props.getProperty("updateType","jar")
         shareDownloadedFiles = Boolean.parseBoolean(props.getProperty("shareDownloadedFiles","true"))
         shareHiddenFiles = Boolean.parseBoolean(props.getProperty("shareHiddenFiles","false"))
+        hashingCores = Integer.parseInt(props.getProperty("hashingCores", String.valueOf(numHashingCores())))
         downloadSequentialRatio = Float.valueOf(props.getProperty("downloadSequentialRatio","0.8"))
         hostClearInterval = Integer.valueOf(props.getProperty("hostClearInterval","15"))
         hostHopelessInterval = Integer.valueOf(props.getProperty("hostHopelessInterval", "60"))
@@ -189,6 +191,7 @@ class MuWireSettings {
         props.setProperty("updateType",String.valueOf(updateType))
         props.setProperty("shareDownloadedFiles", String.valueOf(shareDownloadedFiles))
         props.setProperty("shareHiddenFiles", String.valueOf(shareHiddenFiles))
+        props.setProperty("hashingCores", String.valueOf(hashingCores))
         props.setProperty("downloadSequentialRatio", String.valueOf(downloadSequentialRatio))
         props.setProperty("hostClearInterval", String.valueOf(hostClearInterval))
         props.setProperty("hostHopelessInterval", String.valueOf(hostHopelessInterval))
@@ -283,4 +286,8 @@ class MuWireSettings {
     String getNickname() {
         nickname
     }
+    
+    private static int numHashingCores() {
+        return (int) Math.max(1d, Runtime.getRuntime().availableProcessors() / 2d)
+    }
 }
diff --git a/core/src/main/groovy/com/muwire/core/files/HasherService.groovy b/core/src/main/groovy/com/muwire/core/files/HasherService.groovy
index 43d0f3a5..0df39908 100644
--- a/core/src/main/groovy/com/muwire/core/files/HasherService.groovy
+++ b/core/src/main/groovy/com/muwire/core/files/HasherService.groovy
@@ -34,7 +34,7 @@ class HasherService {
     }
 
     void start() {
-        executor = Executors.newFixedThreadPool((int)Math.max(1d, Runtime.getRuntime().availableProcessors() / 2d ))
+        executor = Executors.newFixedThreadPool(settings.hashingCores)
     }
 
     void onFileSharedEvent(FileSharedEvent evt) {
diff --git a/gui/griffon-app/controllers/com/muwire/gui/OptionsController.groovy b/gui/griffon-app/controllers/com/muwire/gui/OptionsController.groovy
index 653537b0..c64dd0f2 100644
--- a/gui/griffon-app/controllers/com/muwire/gui/OptionsController.groovy
+++ b/gui/griffon-app/controllers/com/muwire/gui/OptionsController.groovy
@@ -103,6 +103,10 @@ class OptionsController {
         boolean shareHidden = view.shareHiddenCheckbox.model.isSelected()
         model.shareHiddenFiles = shareHidden
         settings.shareHiddenFiles = shareHidden
+        
+        int hashingCores = Integer.parseInt(view.hashingCoresTextField.text)
+        model.hashingCores = hashingCores
+        settings.hashingCores = hashingCores
 
         boolean browseFiles = view.browseFilesCheckbox.model.isSelected()
         model.browseFiles = browseFiles
diff --git a/gui/griffon-app/i18n/messages.properties b/gui/griffon-app/i18n/messages.properties
index 88712c8f..48420d07 100644
--- a/gui/griffon-app/i18n/messages.properties
+++ b/gui/griffon-app/i18n/messages.properties
@@ -296,6 +296,7 @@ OPTIONS_UPLOAD_SLOTS_PER_USER=Upload slots per user (-1 means unlimited)
 OPTIONS_SHARING_SETTINGS=Sharing Settings
 OPTIONS_SHARE_DOWNLOADED_FILES=Share downloaded files
 OPTIONS_SHARE_HIDDEN_FILES=Share hidden files
+OPTIONS_HASHING_CORES=CPU Cores to use when hashing (changes require restart)
 OPTIONS_UPDATE_SETTINGS=Update Settings
 OPTIONS_CHECK_FOR_UPDATES=Check for updates every (hours)
 OPTIONS_DOWNLOAD_UPDATES=Download updates automatically
diff --git a/gui/griffon-app/models/com/muwire/gui/OptionsModel.groovy b/gui/griffon-app/models/com/muwire/gui/OptionsModel.groovy
index f90dd03e..addbdb35 100644
--- a/gui/griffon-app/models/com/muwire/gui/OptionsModel.groovy
+++ b/gui/griffon-app/models/com/muwire/gui/OptionsModel.groovy
@@ -17,6 +17,7 @@ class OptionsModel {
     @Observable boolean autoDownloadUpdate
     @Observable boolean shareDownloadedFiles
     @Observable boolean shareHiddenFiles
+    @Observable int hashingCores
     @Observable String downloadLocation
     @Observable String incompleteLocation
     @Observable boolean searchComments
@@ -95,6 +96,7 @@ class OptionsModel {
         autoDownloadUpdate = settings.autoDownloadUpdate
         shareDownloadedFiles = settings.shareDownloadedFiles
         shareHiddenFiles = settings.shareHiddenFiles
+        hashingCores = settings.hashingCores
         downloadLocation = settings.downloadLocation.getAbsolutePath()
         incompleteLocation = settings.incompleteLocation.getAbsolutePath()
         searchComments = settings.searchComments
diff --git a/gui/griffon-app/views/com/muwire/gui/OptionsView.groovy b/gui/griffon-app/views/com/muwire/gui/OptionsView.groovy
index b0bd637a..d2456e29 100644
--- a/gui/griffon-app/views/com/muwire/gui/OptionsView.groovy
+++ b/gui/griffon-app/views/com/muwire/gui/OptionsView.groovy
@@ -49,6 +49,7 @@ class OptionsView {
     def autoDownloadUpdateCheckbox
     def shareDownloadedCheckbox
     def shareHiddenCheckbox
+    def hashingCoresTextField
     def searchCommentsCheckbox
     def searchCollectionsCheckbox
     def browseFilesCheckbox
@@ -172,6 +173,10 @@ class OptionsView {
                 
                 label(text : trans("OPTIONS_SHARE_HIDDEN_FILES"), constraints : gbc(gridx : 0, gridy:1, anchor : GridBagConstraints.LINE_START, weightx : 100))
                 shareHiddenCheckbox = checkBox(selected : bind {model.shareHiddenFiles}, constraints : gbc(gridx :1, gridy:1, weightx : 0))
+                
+                label(text : trans("OPTIONS_HASHING_CORES"), constraints : gbc(gridx: 0 , gridy : 2, anchor : GridBagConstraints.LINE_START, weightx : 100))
+                hashingCoresTextField = textField(text : bind {model.hashingCores}, columns: 2, 
+                    constraints: gbc(gridx: 1, gridy: 2, anchor: GridBagConstraints.LINE_END))
             }
             
             if (!model.disableUpdates) {