WordPress Horizontal Full Categories plugin by byrev shows top level categories and children of categories in horizontal table mode.
ByREV Fast Category Cloud Features:
HTML code and CSS Cache Result. For fast loading and use less resources (default timeout cache = 360s)
Inser CSS in header blog. Result is fewer requests to the server, site load faster
Exclude category with empty posts
Exclude categories option list (by ID)
Ability to use a custom CSS code
Can change the default CSS properties (color, backgrounds, borders)
Management setup menu
Highly optimized for speed and memory
Plugin is divided in two files: 1’st file used by inserting PHP code in template pages, and 2’nd file is used in the WordPress configuration page.
Both files are under 100 lines of code, each have exactly 96 lines each.
Cache help to increase speed, conserve CPU resources and reduce requests to MySQL server
foreach syntax is not used (only for). Less memory used and a higher execution speed.
Where array variables are used repeatedly, pointer variables are used to increase execution speed.
Download and info: http://wordpress.org/extend/plugins/horizontal-full-categories-wordpress-plugin/