selective re-encryption

This is what I think you want:

  
  when HTTP_REQUEST {   
     if {[HTTP::uri] ends_with "gif"} {   
        pool img_pool  
     } else {  
        pool html_secure_pool  
     }  
  }  
  when SERVER_CONNECTED { 
     if {[TCP::remote_port] != 443} { 
        SSL::disable 
     } 
  } 
  

The above example is courtesy of drteeth.

You could even just put the html_secure_pool on the virtual and then remove the "else { pool html_secure_pool }" part of the rule since the pool on the virtual is considered the default pool.