Magento Consuming more than 5GB of Ram on ProductRepository->get($sku)

I have a Problem with my Product Importer. For a bit of Background, we get Products by a RabbitMQ Queue and they get processed by a Model.
Creating Products seems to be no Problem, but if I want to check if a Product already exists I always get an Out of Memory Error.

        $this->logger->debug("Message Received");
        $product = $this->productFactory->create();

        $this->logger->debug("Message Processed");
        $this->logger->debug(print_r($product->getData(),true));
        return true;

This does not work:

        $this->logger->debug("Message Received");
        //$product = $this->productFactory->create();
        $product = $this->productRepository->get((string)$sku);

        $this->logger->debug("Message Processed");
        $this->logger->debug(print_r($product->getData(),true));
        return true;

I tried to start the Cosumer with the option php -dmemory_limit=5G but I still get the following Error: PHP Fatal error: Allowed memory size of 5368709120 bytes exhausted (tried to allocate 3202355200 bytes)

I just can’t imagine that it takes Magento more than 5GB to load a product, is something wrong in the code ?
I took the get function from here:
How to load product by SKU in magento 2

Also I think it does not make sense to have PHP try to allocate around 3054 of around 5000MB and still throwing an oom Error.

Does anyone have an idea what to try here ? Server has 6GB+Swap so that should be enough to load a product I think.

Thanks in advance!