  We study a certain class of arithmetic functions that appeared in Klurman's
classification of $\pm 1$ multiplicative functions with bounded partial sums,
c.f., Comp. Math. 153 (8), 2017, pp. 1622-1657. These functions are periodic
and $1$-pretentious. We prove that if $f_1$ and $f_2$ belong to this class,
then $\sum_{n\leq x}(f_1\ast f_2)(n)=\Omega(x^{1/4})$. This confirms a
conjecture by the first author. As a byproduct of our proof, we studied the
correlation between $\Delta(x)$ and $\Delta(\theta x)$, where $\theta$ is a
fixed real number. We prove that there is a non-trivial correlation when
$\theta$ is rational, and a decorrelation when $\theta$ is irrational.
Moreover, if $\theta$ has a finite irrationality measure, then we can make it
quantitative this decorrelation in terms of this measure.
