I have a late 2012 Mac Mini with 8GB of RAM that is currently running OS X 10.9.5 (Mavericks). Will I notice a performance increase or decrease after updating to Mojave? Will I be able to have a light and cheery desktop background such as the beach or ocean with Mojave? More importantly, will I loose all my books on Safari, emails on Apple Mail or files on iTunes after upgrading? Basic user hoping that I will have a seamless and plug and play transition just by pressing the upgrade button.