OZG-7942 run parallel

alfa-service/src/main/java/de/ozgcloud/alfa/vorgang/VorgangModelAssembler.java

@@ -76,7 +76,7 @@ class VorgangModelAssembler implements RepresentationModelAssembler<Vorgang, Ent
 	RepresentationModel<EntityModel<EnhancedVorgang>> initModel(Stream<VorgangHeader> entities, Statistic statistic) {
 		return HalModelBuilder.halModelOf(EnhancedVorgang.builder().statistic(statistic).build())
 				.link(linkTo(VorgangController.class).withSelfRel())
-				.embed(entities.map(this::toModel).map(linkedResourceProcessor::process))
+				.embed(entities.parallel().map(this::toModel).map(linkedResourceProcessor::process))
 				.build();
 	}