Although I love the e-ink Kindles, I'm not a fan at all of their Fire tablets. They're too locked in to the Amazon ecosystem and without an sd card slot, they are overly limited.
I've found that rooting my Nook HD+ makes it run much faster. I use a dual boot AFN card. They are available with Jelly Bean 4.2.2 or Kit Kat 4.4 and are currently on sale for $11.99 for either version:
http://www.androidfornook.com/nook-s...ownload-detail