I got access to the test server prepared by Ann + J.M. and could test the performance improvements done for the environments with thousands of databases. Even though I could achieve reasonable performance for privileged user, unprivileged users were still seeing long delays. Even 'SHOW DATABASES' queries were as slow as queries on information_schema. The only fast query to access database list was 'SHOW DATABASES LIKE '<db_name>' queries. So the navigation was updated to parse the GRANTS for the user to identify the database he/she has access to and those were used with 'SHOW DATABASES LIKE' queries to get the list of databases.
In addition to the above I attended to the following fixes during the week.
#4577 Multi row actions causes full page reloads
#3481 Designer relations in IE 8 - partial fix
#4582 Debug SQL works only for the first page
#3046 Tracking + MySQL interactive_timeout yields error
#3554 copy paste with middle mouseclick in colored sqlbox
#3073 auth_type signon - odd behaviour at ex- and importing
#4578 Undisclosed vulnerability
#4579 Undisclosed vulnerability
Refactoring Node class of the navigation
P.S: I was on leave on Friday due to personal reasons