Barracks upgrade speed percentage

BB, I upgraded my elite barracks from 4 to 5 and it was suppose to be a 25% speed increase. Level 4 (unbuffed) would produce 1 swordsman in 5 minutes. Level 5 should produce 1 swordsman (unbuffed) in 3 minutes 45 seconds and not in 4 minutes. I'm not sure about previous upgrades or the normal barracks as well but can you look into it? Thanks

It's a 20% increase from level 4-5

It's 25% from base level, not accumulating from the previous level.

As Swordman take 20mins@L1 / L5 > 4 minutes

Just another confusing/misleading/unclear description.