Robin Williams in Dead Poets Society would surely object to this mathematical approach. Or works by the same author. The list of unique words often exposes misspellings. These are some hints that will help make fsconcordance do what you want it to do. The more chapters, the better.
Web clients can only handle so much data at a time.
Loading an entire book into your browser is bad enough, but after fsconcordance is done indexing every single word with a unique number, the resulting html will be very big indeed. Don't cram entire books through your browser. 200k is a good limit to aim for. Separate paragraphs by blank lines. Without blank lines, your text will end up as one big paragraph.