We study semigroups
(
ϕ
t
)
t
≥
0
(\phi _t)_{t\geq 0}
of holomorphic self-maps of the unit disk with Denjoy-Wolff point on the boundary. We show that the orthogonal speed of such semigroups is a strictly increasing function. This answers a question raised by F. Bracci, D. Cordella, and M. Kourou, and implies a domain monotonicity property for orthogonal speeds conjectured by Bracci. We give an example of a semigroup such that its total speed is not eventually increasing. We also provide another example of a semigroup having total speed of a certain asymptotic behavior, thus answering another question of Bracci.