why addLinkedVersionsInfo waste nearly 57sec

[chenzeyun]

i use TL in my new project, but the testplan browser use nearly 1min to back, and the testers comlain a lot

system:
[root@testlink ~]# lsb_release -a
LSB Version: :core-4.0-amd64:core-4.0-noarch:graphics-4.0-amd64:graphics-4.0-noarch:printing-4.0-amd64:printing-4.0-noarch
Distributor ID: CentOS
Description: CentOS release 6.2 (Final)
Release: 6.2
Codename: Final

php file:
/var/www/html/testlink/lib/plan/tc_exec_assignment.php

i use xhprof to profile, the result
Function Name Calls Calls% Incl. Wall Time(microsec) IWall% Incl. CPU(microsecs) ICpu% Incl.MemUse(bytes) IMemUse%Incl.PeakMemUse(bytes) IPeakMemUse%
Current Function
addLinkedVersionsInfo 1 0.0% 76,391,508 95.0% 76,374,389 95.3% 18,968,496 55.2% 19,678,624 17.0%
Exclusive Metrics for Current Function 75,709,413 99.1% 75,712,491 99.1% 2,212,096 11.7% 19,678,624 100.0%
Parent function
gen_spec_view 1 100.0% 76,391,508 100.0% 76,374,389 100.0% 18,968,496 100.0% 19,678,624 100.0%
Child functions
priority_to_level 1,304 19.8% 675,426 0.9% 655,899 0.9% 16,754,864 88.3% 0 0.0%
is_null 2,655 40.4% 4,007 0.0% 2,999 0.0% 768 0.0% 0 0.0%
intval 2,614 39.8% 2,662 0.0% 3,000 0.0% 768 0.0% 0 0.0%

[chenzeyun]

[chenzeyun]

the full callgraph