To go back to this questions:
EFB speeds on 777 vs the FMC.
The FMC speeds provide only raw balanced field speeds. For any airport having obstacles or one requires 'improved climb' amongst other things, these speeds are incorrect.
If you are referring to OPT calculations that are coming off the installed EFB, depending on the operator's requirements, these 'should' be the actual usable V speeds that are to be used for the operation.
OPT speeds come as a result of the usual environmental, weight input but also flight operations engineering input of obstacles, slopes, contaminated runways and improved climb requirements. This list is not exhaustive.
If a crew uses the OPT speeds, it is these V speeds that are 'overwritten' on the takeoff performance page in place of the FMC generated speeds. On the 787, the OPT speeds can be pushed to the FMC and accepted after crosschecks have been made on the data.
Hope it helps.