Krishna on "error 500 and slow site"

Here is a test report that may help you speed up your site. Look at each section and try to optimize.
The report says:

Page load time: 18.98s
Total page size: 2.91MB

Also try to reduce the page size by optimizing images, and reducing the other heavier elements on your friend page.

BTW, it seems there are are attempts to break into your site as the error logs show, though security tools show your site clean.

Review:
http://codex.wordpress.org/Hardening_WordPress
http://codex.wordpress.org/Brute_Force_Attacks