If I encrypt my web page to prevent "visitors" from viewing and reusing my web page source code , will affect my site in search engine?

Simple answer: YES. Encrypt JavaScript if you'd like. Not your HTML code.

Just so you know, it is kind of silly to try to protect your source code. Not only can you not stop someone who is determined from getting it, but you almost certainly don't have anything someone else can't write or mimic themselves. That's why you will never see a remotely serious website trying to hide its source code.

Just put a copyright notice in the code and be prepared to sue if you see someone blatantly flaunting your code. No need to encrypt if you dont have anything to hide

I run my JavaScript code through www.javascriptcompressor.com which does encrypt it, but more importantly (to me, anyways) it compresses it to 1/3rd the size. I think this is important for any site that uses a lot of JavaScript, AJAX, DHTML, etc. because it does really add up.

Is that why the java is slow ;)

No, I've played with both encrypted and non-encrypted versions of the script in an effort to speed it up. I am going to try working with a different javascript UI library in the near future.