diff --git a/kindlecomicconverter/KCC_gui.py b/kindlecomicconverter/KCC_gui.py
index a4622d5..d18cea9 100644
--- a/kindlecomicconverter/KCC_gui.py
+++ b/kindlecomicconverter/KCC_gui.py
@@ -37,7 +37,7 @@ from packaging.version import Version
 from raven import Client
 from tempfile import gettempdir
 
-from .shared import HTMLStripper, sanitizeTrace, walkLevel, subprocess_run
+from .shared import HTMLStripper, available_archive_tools, sanitizeTrace, walkLevel, subprocess_run
 from . import __version__
 from . import comic2ebook
 from . import metadata
@@ -1066,19 +1066,12 @@ class KCCGUI(KCC_ui.Ui_mainWindow):
             self.addMessage('Since you are a new user of <b>KCC</b> please see few '
                             '<a href="https://github.com/ciromattia/kcc/wiki/Important-tips">important tips</a>.',
                             'info')
-        try:
-            subprocess_run(['tar'], stdout=PIPE, stderr=STDOUT)
-            self.tar = True
-        except FileNotFoundError:
-            self.tar = False
-        try:
-            subprocess_run(['7z'], stdout=PIPE, stderr=STDOUT)
-            self.sevenzip = True
-        except FileNotFoundError:
-            self.sevenzip = False
-            if not self.tar:
-                self.addMessage('<a href="https://github.com/ciromattia/kcc#7-zip">Install 7z (link)</a>'
-                                ' to enable CBZ/CBR/ZIP/etc processing.', 'warning')
+        
+        self.tar = 'tar' in available_archive_tools()
+        self.sevenzip = '7z' in available_archive_tools()
+        if not any([self.tar, self.sevenzip]):
+            self.addMessage('<a href="https://github.com/ciromattia/kcc#7-zip">Install 7z (link)</a>'
+                            ' to enable CBZ/CBR/ZIP/etc processing.', 'warning')
         self.detectKindleGen(True)
 
         APP.messageFromOtherInstance.connect(self.handleMessage)
diff --git a/kindlecomicconverter/comic2ebook.py b/kindlecomicconverter/comic2ebook.py
index 9c02f4a..fef6fcf 100755
--- a/kindlecomicconverter/comic2ebook.py
+++ b/kindlecomicconverter/comic2ebook.py
@@ -23,7 +23,7 @@ import pathlib
 import re
 import sys
 from argparse import ArgumentParser
-from time import strftime, gmtime
+from time import perf_counter, strftime, gmtime
 from copy import copy
 from glob import glob, escape
 from re import sub
@@ -40,7 +40,7 @@ from subprocess import STDOUT, PIPE
 from psutil import virtual_memory, disk_usage
 from html import escape as hescape
 
-from .shared import md5Checksum, getImageFileName, walkSort, walkLevel, sanitizeTrace, subprocess_run
+from .shared import available_archive_tools, md5Checksum, getImageFileName, walkSort, walkLevel, sanitizeTrace, subprocess_run
 from . import comic2panel
 from . import image
 from . import comicarchive
@@ -946,17 +946,27 @@ def slugify(value):
 
 
 def makeZIP(zipfilename, basedir, isepub=False):
+    start = perf_counter()
     zipfilename = os.path.abspath(zipfilename) + '.zip'
-    zipOutput = ZipFile(zipfilename, 'w', ZIP_DEFLATED)
-    if isepub:
-        zipOutput.writestr('mimetype', 'application/epub+zip', ZIP_STORED)
-    for dirpath, _, filenames in os.walk(basedir):
-        for name in filenames:
-            path = os.path.normpath(os.path.join(dirpath, name))
-            aPath = os.path.normpath(os.path.join(dirpath.replace(basedir, ''), name))
-            if os.path.isfile(path):
-                zipOutput.write(path, aPath)
-    zipOutput.close()
+    if '7z' in available_archive_tools():
+        if isepub:
+            mimetypeFile = open(os.path.join(basedir, 'mimetype'), 'w')
+            mimetypeFile.write('application/epub+zip')
+            mimetypeFile.close()
+        subprocess_run(['7z', 'a', '-tzip', zipfilename, basedir], capture_output=True, check=True)
+    else:
+        zipOutput = ZipFile(zipfilename, 'w', ZIP_DEFLATED)
+        if isepub:
+            zipOutput.writestr('mimetype', 'application/epub+zip', ZIP_STORED)
+        for dirpath, _, filenames in os.walk(basedir):
+            for name in filenames:
+                path = os.path.normpath(os.path.join(dirpath, name))
+                aPath = os.path.normpath(os.path.join(dirpath.replace(basedir, ''), name))
+                if os.path.isfile(path):
+                    zipOutput.write(path, aPath)
+        zipOutput.close()
+    end = perf_counter()
+    print(f"makeZIP time: {end - start} seconds")
     return zipfilename
 
 
@@ -1131,9 +1141,7 @@ def checkTools(source):
     source = source.upper()
     if source.endswith('.CB7') or source.endswith('.7Z') or source.endswith('.RAR') or source.endswith('.CBR') or \
             source.endswith('.ZIP') or source.endswith('.CBZ'):
-        try:
-            subprocess_run(['7z'], stdout=PIPE, stderr=STDOUT)
-        except FileNotFoundError:
+        if '7z' not in available_archive_tools():
             print('ERROR: 7z is missing!')
             sys.exit(1)
     if options.format == 'MOBI':
diff --git a/kindlecomicconverter/shared.py b/kindlecomicconverter/shared.py
index d98c5de..76c579f 100644
--- a/kindlecomicconverter/shared.py
+++ b/kindlecomicconverter/shared.py
@@ -18,6 +18,7 @@
 # PERFORMANCE OF THIS SOFTWARE.
 #
 
+from functools import lru_cache
 import os
 from hashlib import md5
 from html.parser import HTMLParser
@@ -137,6 +138,19 @@ def dependencyCheck(level):
         print('ERROR: ' + ', '.join(missing) + ' is not installed!')
         sys.exit(1)
 
+@lru_cache
+def available_archive_tools():
+    available = []
+
+    for tool in ['tar', '7z', 'unar', 'unrar']:
+        try:
+            subprocess_run([tool], stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
+            available.append(tool)
+        except FileNotFoundError:
+            pass
+    
+    return available
+
 def subprocess_run(command, **kwargs):
     if (os.name == 'nt'):
         kwargs.setdefault('creationflags', subprocess.CREATE_NO_WINDOW)