Little to no performance improvement. Whether it's a single partition or 10 partitions, they're just logical ways of dividing up the same physical drive. It's like reading through a book that uses the standard chapter/page/paragraph format, versus a book that omits the chapter separators. It's still a single book, & you still have to flip through it to find the page you're looking for. Chapters can help you organize it more effectively, but they don't help you read it any faster.
Mainly, what it's going to do is allow you to better organize your files & apps on the hard drive. Setting up 2 partitions helps you track better what's taking up your storage space, & gives you a better handle on when you might need to add more storage...