The longer loading times (on the first call) are normal for many variants, as each one has to be loaded. Please note that the matrix will not be created if the variants are not loaded. Server performance is also relevant. For very large variants, it may be worth using a cache warmer.
The licence from Shopware 5 cannot be transferred to Shopware 6. However, if you start the migration assistant in your Shopware account, you can purchase the new plugin licence at a reduced price. (as of March 2024)
