Lemma 74.13.5. Let $X$ be a scheme. Let $E$ be an object of $D(\mathcal{O}_ X)$. Then $E$ is a perfect object of $D(\mathcal{O}_ X)$ if and only if $\epsilon ^*E$ is a perfect object of $D(\mathcal{O}_{\acute{e}tale})$. Here $\epsilon $ is as in (74.4.0.1).

**Proof.**
The easy implication follows from the general result contained in Cohomology on Sites, Lemma 21.47.5. For the converse, we can use the equivalence of Cohomology on Sites, Lemma 21.47.4 and the corresponding results for pseudo-coherent and complexes of finite tor dimension, namely Lemmas 74.13.2 and 74.13.3. Some details omitted.
$\square$

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