Dreamweaver gives a lot of options, like a Live preview, split the live preview and codes, and many others options in the footer, and sidebar sections.
Can I disable it's some features to increase its performance?
Sadly you cannot disable whole "sections/modules" of the program there are however quite a few things you can do before you just replace it with Notepad++ ;)
I found a comprehensive list here http://sniptools.com/vault/speed-up-dreamweaver-mx-some-performance-boosting-tips, some of these look really useful: