title: Update panel send all the page to the server
body: <p>Good morning everyone, I have a page with a section on the left (an ascx control) with an updatepanel and on the right the remaining part of the page.
  The update panel here works pretty well and I am happy for its job.</p>
  
  <p>However in another page I have the same ascx control on the left and tens of pictures on the right.When I use here the dropdown on the left menu (contained in the updatepanel), before to receive serverside the command takes a lot of time and by my opinion is due the browser is uploading all the info (pictures,.. in general the whole page ) again to the server.</p>
  
  <p>Is it possible this my assumption, I haven't found advice on internet and I have a big problem of performance.</p>
  
  <p>Just to highlight one thing the update panel is working , I am correctly updating only the update panel without a full postback, the problem is during the server call that takes time ....</p>
  
  <p>Kind Regards,</p>
  
  <p>luca</p>