Hi!
Right you asked. We actually nailed it last week, despite the lack of feedback from Lattice.
The guilty is not the full EFB block, but just the internal oscillator, that you need to explicitly instantiate, and tie its STDBY port to logic "1".
OSCH OSCH_inst(
.STDBY ( 1'b1), // 0=Enabled, 1=Disabled
.OSC ( ),
.SEDSTDBY ( ) // this signal is not required
) /* synthesis syn_noprune=1 */;
This will remove the 5mW power consumption offset in the design (on board measurement performed to validate).
And for the power estimator, when you have correctly synthesized your design with the disabled internal oscillator, in the Power Control button, you have the "Disable OSC" field available that you can tick. That will remove the 5mW offset in the power estimator.
Hope it helps,
Regards,
/P