slow usermng

[AleksM]

hello!
we have ~ 24k users on the one server
we create new accounts with plesk api
all steps is very fast except psa/admin/bin/usermng --add-user
this command eats 100% CPU and work ~2 min
(simple useradd linux command works very fast)
when I tried to attach to usermng process with strace it shows

open("/etc/passwd", O_RDONLY|0x80000 /* O_??? */) = 3
lseek(3, 0, SEEK_CUR) = 0
fstat(3, {st_mode=S_IFREG|0644, st_size=1713592, ...}) = 0
mmap(NULL, 1713592, PROT_READ, MAP_SHARED, 3, 0) = 0x7ffb814f0000
lseek(3, 1713592, SEEK_SET) = 1713592
munmap(0x7ffb814f0000, 1713592) = 0
close(3)

a lot of times

I can't determinate for what this
so question : is it possible to speed up this step ?

 

[AleksM]

Ubuntu server 8.04 (latest updates)
Parallels Plesk Panel version 9.5.3