Chapter 17 Traffic Shaping for FortiOS 5.0 : Traffic shaping methods : Application control shaping
  
Application control shaping
Traffic shaping is also possible for specific applications for both shared and per IP shaping. Through the Security Profiles > Application Control feature, you can configure a specific application’s maximum bandwidth. When configuring the application control features, if the application is set to pass, you can set the traffic shaping options. The shapers available are those set up in the Firewall Objects > Traffic Shaping menu.
For more information on configuring application control shapers, see the Security Profiles Guide.
See also 
Shared policy shaping
Per-IP shaping
Enabling in the security policy
Type of Service priority
Differentiated Services
Tos and DSCP mapping
Traffic Shaper Monitor