A graph $G$ is $k$-critical (list $k$-critical, DP $k$-critical) if $χ(G)= k$ ($χ_\ell(G)= k$, $χ_\mathrm{DP}(G)= k$) and for every proper subgraph $G'$ of $G$, $χ(G')<k$ ($χ_\ell(G')< k$, $χ_\mathrm{DP}(G')<k$). Let $f(n, k)$ ($f_\ell(n, k), f_\mathrm{DP}(n,k)$) denote the minimum number of edges in an $n$-vertex $k$-critical (list $k$-critical, DP $k$-critical) graph. The main result of this paper is that if $n\geq 6$ and $n\not\in\{7,10\}$, then $$f_\mathrm{DP}(n,4)>\left(3 + \frac{1}{5} \right) \frac{n}{2}. $$ This is the first bound on $f_\mathrm{DP}(n,4)$ that is asymptotically better than the well-known bound $f(n,4)\geq \left(3 + \frac{1}{13} \right) \frac{n}{2}$ by Gallai from 1963. The result also yields a better bound on $f_{\ell}(n,4)$ than the one known before.