Stratum Fact No. 6:

If you just installed SV2 firmware on your device (your ASIC) and *nothing* else, Braiins estimates a ~35% efficiency gain compared to the SV1 firmware that the manufacturer initially puts on the device (OEM)! 

Miners that switch their firmware to SV2 are rewareded with smaller SV2 message sizes and added security. 

Source: page 16 of this doc  https://docsend.com/view/szk48syby33q28zq