Improve performance of checking path extension

src/base/path.cpp

@@ -155,7 +155,9 @@ QString Path::extension() const
 
 bool Path::hasExtension(const QString &ext) const
 {
-    return (extension().compare(ext, Qt::CaseInsensitive) == 0);
+    Q_ASSERT(ext.startsWith(QLatin1Char('.')));
+
+    return m_pathStr.endsWith(ext, Qt::CaseInsensitive);
 }
 
 bool Path::hasAncestor(const Path &other) const

src/gui/uithememanager.cpp

@@ -141,7 +141,7 @@ namespace
         if (themePath.filename() == CONFIG_FILE_NAME)
             return std::make_unique<FolderThemeSource>(themePath);
 
-        if ((themePath.extension() == QLatin1String(".qbtheme"))
+        if ((themePath.hasExtension(QLatin1String(".qbtheme")))
                 && QResource::registerResource(themePath.data(), QLatin1String("/uitheme")))
         {
             return std::make_unique<QRCThemeSource>();