diff --git a/share/qt/Info.plist.cmake.in b/share/qt/Info.plist.cmake.in
--- a/share/qt/Info.plist.cmake.in
+++ b/share/qt/Info.plist.cmake.in
@@ -97,9 +97,6 @@
   <key>NSHighResolutionCapable</key>
     <string>True</string>
 
-  <key>LSAppNapIsDisabled</key>
-    <string>True</string>
-
   <key>LSApplicationCategoryType</key>
     <string>public.app-category.finance</string>
 </dict>
diff --git a/src/qt/CMakeLists.txt b/src/qt/CMakeLists.txt
--- a/src/qt/CMakeLists.txt
+++ b/src/qt/CMakeLists.txt
@@ -140,6 +140,7 @@
 	target_sources(bitcoin-qt-base PRIVATE
 		macdockiconhandler.mm
 		macnotificationhandler.mm
+		macos_appnap.mm
 	)
 
 	set_property(TARGET bitcoin-qt-base PROPERTY AUTOMOC_MOC_OPTIONS "-DQ_OS_MAC")
diff --git a/src/qt/bitcoingui.h b/src/qt/bitcoingui.h
--- a/src/qt/bitcoingui.h
+++ b/src/qt/bitcoingui.h
@@ -20,6 +20,10 @@
 #include <QPoint>
 #include <QSystemTrayIcon>
 
+#ifdef Q_OS_MAC
+#include <qt/macos_appnap.h>
+#endif
+
 #include <memory>
 
 class ClientModel;
@@ -170,6 +174,10 @@
     HelpMessageDialog *helpMessageDialog = nullptr;
     ModalOverlay *modalOverlay = nullptr;
 
+#ifdef Q_OS_MAC
+    CAppNapInhibitor *m_app_nap_inhibitor = nullptr;
+#endif
+
     /** Keep track of previous number of blocks, to detect progress */
     int prevBlocks = 0;
     int spinnerFrame = 0;
diff --git a/src/qt/bitcoingui.cpp b/src/qt/bitcoingui.cpp
--- a/src/qt/bitcoingui.cpp
+++ b/src/qt/bitcoingui.cpp
@@ -208,6 +208,10 @@
                 &BitcoinGUI::showModalOverlay);
     }
 #endif
+
+#ifdef Q_OS_MAC
+    m_app_nap_inhibitor = new CAppNapInhibitor;
+#endif
 }
 
 BitcoinGUI::~BitcoinGUI() {
@@ -221,6 +225,7 @@
         trayIcon->hide();
     }
 #ifdef Q_OS_MAC
+    delete m_app_nap_inhibitor;
     delete appMenuBar;
     MacDockIconHandler::cleanup();
 #endif
@@ -1068,6 +1073,14 @@
 
 void BitcoinGUI::setNumBlocks(int count, const QDateTime &blockDate,
                               double nVerificationProgress, bool header) {
+// Disabling macOS App Nap on initial sync, disk and reindex operations.
+#ifdef Q_OS_MAC
+    (m_node.isInitialBlockDownload() || m_node.getReindex() ||
+     m_node.getImporting())
+        ? m_app_nap_inhibitor->disableAppNap()
+        : m_app_nap_inhibitor->enableAppNap();
+#endif
+
     if (modalOverlay) {
         if (header) {
             modalOverlay->setKnownBestHeight(count, blockDate);
diff --git a/src/qt/macos_appnap.h b/src/qt/macos_appnap.h
new file mode 100644
--- /dev/null
+++ b/src/qt/macos_appnap.h
@@ -0,0 +1,23 @@
+// Copyright (c) 2011-2018 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_QT_MACOS_APPNAP_H
+#define BITCOIN_QT_MACOS_APPNAP_H
+
+#include <memory>
+
+class CAppNapInhibitor final {
+public:
+    explicit CAppNapInhibitor();
+    ~CAppNapInhibitor();
+
+    void disableAppNap();
+    void enableAppNap();
+
+private:
+    class CAppNapImpl;
+    std::unique_ptr<CAppNapImpl> impl;
+};
+
+#endif // BITCOIN_QT_MACOS_APPNAP_H
diff --git a/src/qt/macos_appnap.mm b/src/qt/macos_appnap.mm
new file mode 100644
--- /dev/null
+++ b/src/qt/macos_appnap.mm
@@ -0,0 +1,68 @@
+// Copyright (c) 2011-2018 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include "macos_appnap.h"
+
+#include <AvailabilityMacros.h>
+#include <Foundation/Foundation.h>
+#include <Foundation/NSProcessInfo.h>
+
+class CAppNapInhibitor::CAppNapImpl {
+public:
+    ~CAppNapImpl() {
+        if (activityId) {
+            enableAppNap();
+        }
+    }
+
+    void disableAppNap() {
+        if (!activityId) {
+            @autoreleasepool {
+                const NSActivityOptions activityOptions =
+                    NSActivityUserInitiatedAllowingIdleSystemSleep &
+                    ~(NSActivitySuddenTerminationDisabled |
+                      NSActivityAutomaticTerminationDisabled);
+
+                id processInfo = [NSProcessInfo processInfo];
+                if ([processInfo respondsToSelector:@selector
+                                 (beginActivityWithOptions:reason:)]) {
+                    activityId = [processInfo
+                        beginActivityWithOptions:activityOptions
+                                          reason:@"Temporarily disable App Nap "
+                                                 @"for bitcoin-qt."];
+                    [activityId retain];
+                }
+            }
+        }
+    }
+
+    void enableAppNap() {
+        if (activityId) {
+            @autoreleasepool {
+                id processInfo = [NSProcessInfo processInfo];
+                if ([processInfo respondsToSelector:@selector(endActivity:)]) {
+                    [processInfo endActivity:activityId];
+                }
+
+                [activityId release];
+                activityId = nil;
+            }
+        }
+    }
+
+private:
+    NSObject *activityId;
+};
+
+CAppNapInhibitor::CAppNapInhibitor() : impl(new CAppNapImpl()) {}
+
+CAppNapInhibitor::~CAppNapInhibitor() = default;
+
+void CAppNapInhibitor::disableAppNap() {
+    impl->disableAppNap();
+}
+
+void CAppNapInhibitor::enableAppNap() {
+    impl->enableAppNap();
+}