The main areas of dissipation in an SMPS are (Buck topology)...
1. Driving losses to the MOSFETS/IGBTs. Increases with frequency, independent of duty cycle.
2. Switching losses. Increases with frequency, independent of duty cycle.
3. Diode losses. Independent of frequency, Increases with duty cycle.
4. Capacitor ESR losses. Decreases with frequency.
5. Inductor resistance. Independent of frequency, increases with duty cycle.
That's all I can think of before coffee...