Links are to gprof output, function .mcount is the profilling function.
1.0b6 1.0b6-chainedhash
# time /usr/local/bin/nagios -v /usr/local/etc/nagios/nagios.cfg 

[Output]
real    0m12.019s
user    0m11.687s
sys     0m0.329s

again:
real    0m11.807s
user    0m11.752s
sys     0m0.048s
real    0m8.307s
user    0m6.922s
sys     0m0.379s

again:
real    0m8.117s
user    0m6.922s
sys     0m0.398s
mozilla load times:
tac.cgi: 18.855 seconds
extinfo.cgi?&type=0: 13.826 seconds
extinfo.cgi?&type=7: 31.998 seconds
status.cgi?host=all: 119.472 seconds
status.cgi?hostgroup=all: 39.363 seconds
status.cgi?hostgroup=all&style=summary: 154.699 seconds
status.cgi?hostgroup=all&style=grid: 32.005 seconds
tac.cgi: 4.251 seconds
extinfo.cgi?&type=0: 3.414 seconds
extinfo.cgi?&type=7: 22.665 seconds
status.cgi?host=all: 95.759 seconds
status.cgi?hostgroup=all: 18.065 seconds
status.cgi?hostgroup=all&style=summary: 8.914 seconds
status.cgi?hostgroup=all&style=grid: 19.523 seconds
nagios running normally for ~10m:

# time /usr/local/bin/nagios /usr/local/etc/nagios/nagios.cfg 
real    10m12.795s
user    6m32.515s
sys     3m26.980s

again:
real    10m10.340s
user    6m31.720s
sys     3m21.807s
real    10m5.988s
user    6m9.895s
sys     3m42.274s

again:
real    10m3.585s
user    6m8.282s
sys     3m43.587s
Chained Hash Patch to 1.0b6