I have to reopen this ticket, because changes in 19852 worsened this problem (data from GlotPress):
- WP 3.3.1 - 3491 (standard), 482 (multisite)
- Trunk - 1644 (frontend), 2194 (backend), 260 (multisite admin)
So, in WP 3.3.1 there were 3491 standard strings loaded in administration. But in current trunk this number was radically increased to 3838 (1644 + 2194) strings (!). Specially for multisite was loaded 482 strings (and I wanted to increase this number), but now there are only 260 strings. It is too bad for localized versions, much more memory and no sense to load things which are not needed for most users...
Yes, change in 19852 is very positive for loading only frontend strings, but really problematic for working in backend. I think the best approach would be marking all multisite strings with special textdomain which could lead to increase in multisite strings to more than 600.
Strings shouldn't be duplicated in the backend. The admin strings are also loaded in the default textdomain and during the loading procedure the new and old values are merged, not appended to each other.
Do you have any specific tests to show that the memory usage increased, because of that change?