I have to set up a bunch of drupal sites within the next month. So in the moment I am testing the actual cvs/pre-4.5. version to find out what is the best solution. The recent download provides a new locale module (PO files upload etc.) with some improvements.
I am not happy to report that the new locale results in a tremendous performance reduction especially with older and slower servers.
The speed reduction (devel) is between 800% (slower server & small percentage of transl. strings) and more than 2000% (faster server & a biger amount aof transl. strings) compared to a setting with locale disabled or english as default.
Drupal with new locale "adds" more speed reduction to faster machines than to slow server - relative to settings with locale disabled ord english selected. This looks like a sort of compensation: One can take away more power from the powerful, because enough strength remains; one cannot take away too much power from the less powerful because of the apparent weakness (this is not a competent technical explanation)
Values are page execution time (ms) provided by devel, start page was called
SERVER 1: 2x Intel(R) Xeon(TM) CPU 3.06GHz, 2 GB mem, 3 SCSI 76GB, RAID 5, Freebsd 4.10, Apache/2.0.50, PHP/4.3.8
SERVER 2: 1x AMD Athlon(tm) XP 1700+, 1 GB mem, 1 IDE HD 60 GB, Apache/1.3.31, PHP/4.3.8
SERVER 3: 2x Pentium II Xeon/400Mhz, 512 MB mem, 1 SCSI 4GB + 1 SCSI 8 GB, Freebsd 4.10, Apache/2.0.50, PHP/4.3.8