Avoid using QString::split

We are only interested in the first element of the splitted string, but split will compute all of them. This has some significant performance impact. Instead use indexOf+left to get the first element

kerfuffle/jobs.cpp

@@ -331,7 +331,8 @@ void LoadJob::onNewEntry(const Archive::Entry *entry)
             fullPath = fullPath.remove(0, 2);
         }
 
-        const QString basePath = fullPath.split(QLatin1Char('/')).at(0);
+        const int index = fullPath.indexOf(QLatin1Char('/'));
+        const QString basePath = fullPath.left(index);
 
         if (m_basePath.isEmpty()) {
             m_basePath = basePath;