After further troubleshooting, I found it was the WooCommerce dashboard widget that was very slow, particularly when using MYISAM tables.
I resolved it by using the following function to remove the wooCommerce dashboard widget:
function remove_dashboard_widgets(){
// remove WooCommerce Dashboard Status
remove_meta_box( ‘woocommerce_dashboard_status’, ‘dashboard’, ‘normal’);
}
add_action(‘wp_user_dashboard_setup’, ‘remove_dashboard_widgets’, 20);
add_action(‘wp_dashboard_setup’, ‘remove_dashboard_widgets’, 20);
