Slow combo box when adding 500 rows

[Osmo Antero <osmoma gmail com>]

Hello,
Adding rows to a combo box with a GtkListStore is immensely slow.
Is it right that adding 500 rows can take upto 10 seconds and the GUI freezes?

I have also tested gtk_combo_box_text_new_with_entry() and it is equally slow.

Here is a complete test code based on gtk 3.0:
http://www.futuredesktop.org/tmp/test1.c

Version of Gtk is:
$ pkg-config --modversion gtk+-3.0
3.4.1

This laptop has:
$ cat /proc/cpuinfo
processor cores: 7
vendor_id       : GenuineIntel
model name      : Intel(R) Core(TM) i7-2670QM CPU @ 2.20GHz

Memory:
$ cat /proc/meminfo
MemTotal:  8 GB

Operating system is:
$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 12.04 LTS
Release:        12.04
Codename:       precise

What is your opinion?
Should I use a thread to add data after the GUI has been displayed?

Kindly
Osmo Antero
http://www.futuredesktop.org