I'm new to WP. Is it common for new releases to screw everything up??
No, WordPress 3.0 (like most major releases) was tested by several hundred volunteers over the course of about six months. Most of the current issues are related to plugin conflicts involving functions which were warned of being deprecated way back in WordPress 2.9.
If you run into slow loading:
1. Manually run
/wp-admin/upgrade.php (visit it in your browser).
2. Try decativating all plugins. If that resolves the issue, reactivate each one individually until you find the cause.
3. Try switching to the Twenty Ten theme to rule-out a theme-specific issue.
4. Download WordPress again and delete then replace your copies of the
/wp-includes/ directories with fresh copies from the download.
5. Access your WordPress database via phpMyAdmin (most hosting providers offer this in their control panel), check all of the tables, and choose "Optimize tables" from the pull-down menu.
6. Try installing the Memory Bump plugin.
7. If nothing else works, try these methods to increase PHP's memory allocation:
1. If you have access to your PHP.ini file, change the line in PHP.ini
If your line shows 32M try 64M:
memory_limit = 64M ; Maximum amount of memory a script may consume (64MB)
2. If you don't have access to PHP.ini try adding this to an .htaccess file:
php_value memory_limit 64M
3. Try adding this line to your wp-config.php file:
Increasing memory allocated to PHP
4. Talk to your host.