I have opened issue2551153 to expose timing data as Server-Timing
headers.

This should make it available to various development tools.

Also you can add a stat reporting to templating utils to get
response time.

E.G. in extensions/templating.py add:

  def report_stats(client):
    return '<p><small>Generated in %0.3fs<small></p>\n'%(time.time()-
client.start)

call it in page.html using:

  <div tal:replace="structure 
python:utils.report_stats(request.client)"></div>