title: Why does IE "paint" function create lag when editing textarea?
body: <p>We're experiencing a fairly annoying lag in typing whenever our web application is used via Citrix VDI. The lag is most noticeable on a modal dialog where the user can edit a comment field. The dialog is standard bootstrap:</p>
  <pre><code>&lt;div class=&quot;modal&quot; id=&quot;id_ov_notes_editor&quot; data-backdrop=&quot;static&quot; data-keyboard=&quot;true&quot; tabindex=&quot;-1&quot; role=&quot;dialog&quot; aria-labelledby=&quot;myModalLabel&quot; aria-hidden=&quot;true&quot;&gt;
      &lt;div class=&quot;modal-body&quot;&gt;
          &lt;div class=&quot;well&quot;&gt;
              &lt;div class=&quot;row&quot;&gt;
                  &lt;div class=&quot;col-sm-12&quot;&gt;
                      &lt;textarea id=&quot;id_ov_notes_editor_textarea&quot; class=&quot;form-control&quot; rows=&quot;25&quot;&gt;&lt;/textarea&gt;
                  &lt;/div&gt;
              &lt;/div&gt;
          &lt;/div&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  <p>We only see the lag in Internet Explorer (10 and 11), and only on Citrix.</p>
  <p><a href="https://i.stack.imgur.com/Mdbrr.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Mdbrr.png" alt="screenshot " /></a><br />
  <sub>(source: <a href="https://www.umbrella.ch/simon/ui-responsiveness.png" rel="nofollow noreferrer">umbrella.ch</a>)</sub></p>
  <p>The top portion shows the IE &quot;UI Responsiveness&quot; summary for IE running on Citrix VDI. The bottom portion shows the same user interaction using a IE running on my local PC. Both times, the only action is to type text into the textarea. The purple part is attributed to the IE &quot;Paint&quot; function, taking up 17% time on the local PC, but 61% on Citrix VDI.</p>
  <p>Why does &quot;Paint&quot; take up so much time on the Citrix VDI? Is there anything we can do in our web application to reduce this? Is there any VDI setting?</p>
  <p><strong>EDIT:</strong>
  Further tests show that the lag is directly dependent on the display size of the textarea. With a simple HTML showing only a textarea, the lag is not noticeable with a rather small browser window, and increases dramatically when maximizing the window.</p>
  <p>Thanks
  Simon</p>