bottleneck in the admin system

[ErikI1]

Hi, when user has a lot of sites for administration (>500), the admin system slows down significantly - each click takes more than one second longer. it is due a gradual reading of all options for each relevant site:

SELECT wp_blogs.blog_id FROM wp_blogs WHERE wp_blogs.blog_id IN ( 1,9..... ) AND archived = '0' AND spam = 0 AND deleted = 0;
SELECT * FROM wp_blogs WHERE blog_id IN (9,10,...);
SELECT option_name, option_value FROM wp_options WHERE autoload = 'yes';
SELECT option_name, option_value FROM wp_9_options WHERE autoload = 'yes';
SELECT option_name, option_value FROM wp_10_options WHERE autoload = 'yes';

Probably problem is in bar menu which call this function user_has_networks for each click. with a large number of networks, switching through the bar is not functional anyway, since they cannot all fit there and scrolling is not possible. it would be good to optimize this functionality or introduce the possibility to turn off network switching via the bar or add search for it.