At first, the number of characters in this new novel worried me. But while reading the definition of high fantasy, I realized my concern is unfounded. Created-world fiction is often epic in scope, which by definition requires a great number of characters.
To find all my names, I have researched medieval censuses, translated words into modern foreign languages and pillaged word parts from them, and fiddled with spellings of common names.
For place names, I've often plundered this book:
Of particular delight and frustration to me is rereading Rothfuss' epic and discovering how often he invented superfluous names for an object or idea and has kept/incorporated them all rather than picking his favorite to use. In other words, he is such a talented namer he has over-named almost everything. And I love it. It reflects a truth of language and naming. And to do that in a book where the very act of naming is central to plot and philosophy is brilliant.
I have been pleased to see that none of my names are in the Kingkiller Chronicles, though one of my favorites unintentionally combines pieces of two of his character names. Hard to avoid, really. I'm sure we are drawing from similar sources.
As Mark Twain said (so you know it's true):
“There is no such thing as a new idea. It is impossible. We simply take a lot of old ideas and put them into a sort of mental kaleidoscope. We give them a turn and they make new and curious combinations. We keep on turning and making new combinations indefinitely; but they are the same old pieces of colored glass that have been in use through all the ages.”
― Mark Twain, Mark Twain's Own Autobiography: The Chapters from the North American Review