I don't think there is a way you can read very fast while you're learning the language. It is bound to be a slow process until you get closer to fluency. But I understand the need not be slowed down too much when you read. If your reading speed is too slow, it is harder to stay interested in the ideas presented in the book. One way to help reduce the dictionary lookup time is to read online with quick lookup tools. Browser-based pop-up dictionaries let you look up the definition with just a click without leaving the page. Google Dictionary is one such tool. Certain sites (like LingQ.com) also provide similar features. Another way is to read the target language text with your native language translation next to it. Reading them side by side, you can get help on whole sentences and paragraphs from the translation when necessary. Using these aids appropriately, you can skim over less important passages with a minimum of interruptions and only check the full definitions and usages for what you think is more important.