Melior quam Perseus est?

No Dictionaries

This site is comparable to Perseus as an online source for Latin texts with help. No Dictionaries's list of texts is not as extensive as Perseus', but it covers many of the essentials. And it is definitely faster.
As with Perseus, you can click on individual words for definitions still and you get the dictionary entry immediately under the word.
There's another option as well. While you're reading the text, there's a bar on the right hand side of the page that you can slide. Depending where you slide the bar, it will show more or fewer words' dictionary entries.
Unlike Perseus, you don't have a grammatical breakdown of a word: tense and mood for verbs, case and number for nouns. But if you already know you're the kind of person with a fairly solid grammar but needs quick help with vocabulary, this may be the superior site.

A caveat of course. I was trained to have as little English on the Latin text itself as possible. No writing your translation in the spaces between the lines. I was told that keeps you in decoding mode and that you'll move more slowly toward real reading skills. At least with Perseus definitions come up in another window and the Latin text remains intact. But this may have been a personal preference of my professor, and you are free to disagree with this philosophy, in which case you may prefer No Dictionaries.