Commonly if your answer to "does it also occur with midori -p" is "yes" it points towards a WebKit/ JavascriptCore problem. As it doesn't we can assume it's something not found in private browsing, for example anything related to writing files (use strace to watch for excessive activity), DBus, extensions, session management. Still if I advise you to investigate any of these it's a shot in the dark, I have no concrete leads and that's why I refrained from specific suggestions.
Commonly if your answer to "does it also occur with midori -p" is "yes" it points towards a WebKit/ JavascriptCore problem. As it doesn't we can assume it's something not found in private browsing, for example anything related to writing files (use strace to watch for excessive activity), DBus, extensions, session management. Still if I advise you to investigate any of these it's a shot in the dark, I have no concrete leads and that's why I refrained from specific suggestions.