title: Android webview loading data performance very slow
body: <p>Hi I am working on one application, In that I am using Android WebView.
  Whenever I launch webview activity, loading data in string html format from test.txt file.
  test.txt file contains nearly 2.5 MB data, after loading test.txt file, if slide screen to end to read all data and press back.
  Then subsequent launch of webview activity taking more time to render data. In first launch of webview its taking minimal time.
  I am not getting any error/exception/crash in between launching this activity.</p>
  
  <p>I am using Android API level 18 and above</p>
  
  <p><strong>Note:</strong> I did lot of research on this issue. I tried Solution from <a href="https://stackoverflow.com/questions/7422427/android-webview-slow">Android webview slow</a> and <a href="https://stackoverflow.com/questions/4081250/android-webview-performance">Android WebView performance</a> no use.</p>
  
  <p>I can't make <strong>android:hardwareAccelerated="true"</strong> &lt;-- why because it has lot of side effects (Still I used this one, but no changes I found on this issue). </p>
  
  <p>I can't use 
  <strong>webview.getSettings().setRenderPriority(RenderPriority.HIGH);</strong></p>
  
  <p><strong>setRenderPriority()</strong> --> This method was deprecated in API level 18. 
                          It is not recommended to adjust thread priorities, and this will not be supported in future versions.</p>
  
  <p>My DataLoader.java class</p>
  
  <pre><code>public class DataLoader extends Activity {
  
      private WebView webView = null;
      // Progress Dialog
      private ProgressDialog progressDialog;
  
      String dataContent = null;
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
  
          setContentView(R.layout.web_view);
          webView = (WebView)findViewById(R.id.text);
  
          // Loading webview in Background Thread
          new LoadWebView().execute();
      }
  
      class LoadWebView extends AsyncTask&lt;String, String, String&gt; {
  
          @Override
          protected void onPreExecute() {
              super.onPreExecute();
              progressDialog = new ProgressDialog(DataLoader.this);
              progressDialog.setTitle("Loading...");
              progressDialog.setMessage("Please wait.");
              progressDialog.setCancelable(false);
              progressDialog.setIndeterminate(true);
              progressDialog.show();
          }
  
          protected String doInBackground(String... args) {
              // AssetFileReader read the txt file and return data in the form of string
              dataContent = AssetFileReader.read(getApplicationContext(), "test.txt");
  
              return null;
          }
  
          protected void onPostExecute(String str) {
              // dismiss the dialog
              progressDialog.dismiss();
  
              if (dataContent != null) {
                  // updating UI from Background Thread
                  runOnUiThread(new Runnable() {
                      public void run() {
  
                          WebSettings s = webView.getSettings();
                          s.setUseWideViewPort(true);
                          s.setSupportZoom(true);
                          s.setBuiltInZoomControls(true);
                          s.setDisplayZoomControls(false);
                          s.setJavaScriptEnabled(true);
                          webView.loadData(dataContent, "text/html", "utf-8");
                      }
                  });
              }
          }
      }
  
      @Override
      public void onDestroy() {
          super.onDestroy();
          webView.clearCache(true);
          webView.clearHistory();
      }
  }
  </code></pre>
  
  <p>my web_view.xml file</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:orientation="vertical"&gt;
  
      &lt;WebView
          android:layout_width="fill_parent"
          android:layout_height="fill_parent"
          android:id="@+id/text"&gt;
      &lt;/WebView&gt;
  
  &lt;/LinearLayout&gt;
  </code></pre>
  
  <p>please let me know if you have any work around on this issue.</p>