Extra 1% of base crafting speed to enable continous launches. Silo with 4 prod-3 modules and 20 beacons with speed-3 modules results in 3.31 rocket parts per second. You need >=3.34 per second to skip door opening/closing animation. This 1% base bonus multiplied by effect of 20 beacons is just enough.
Small changes concerning balance, gameplay, or graphics.