I have over 40,000 users in my database. Unfortunately wordpress now does not allow me to search (in the network admin) or browse (choose "all users" in the cpanel) the users in any blog. It will either timeout with a blank page or will yield the error below. I am guessing that it is because there is a join somewhere that makes this slowdown occur. A few years ago someone made a change to the code that seemed to alleviate this problem and I'm unable to determine what they did. Does anyone else have this problem? If so, how have you solved it? Right now I'm getting slow queries and:
Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 32 bytes) in /home/mysite/public_html/wp-includes/meta.php on line 563
If you try to browse all users. There isn't any reason I should require 512MB of php execution memory just do do a simple search of users or to be able to see the first 20 users in my database before performing a search.