I found that caching mechanism doesn't work for the windows. Maybe there are something incompatible across platform. I'm not sure if the following causes the problem:
in Application.php, at line 525: $this->_conf['cache_dir'] = '/tmp';
in Cache.php, at line 39: $cachedir = '/tmp';
in DB.php, at line 315: $fp = fopen('/tmp/querylog.log', 'a');
Can somebody fix this problem by using the sys_get_temp_dir() function for these hard-coded directory, so we can take advantage of the built-in cache?