gpg-agent prompt slow to show up

[Charlie Brown]

> First, how did you install GnuPG?  What OS / distribution are you
> using?  What configuration options are you using (gpg-agent.conf and
> gpg.conf)?

Sorry for the lack of information. I'm on Debian unstable, and
installed GnuPG using apt-get.
--------------gpg.conf-------------
no-greeting
keyserver hkp://keys.gnupg.net
use-agent
----------gpg-agent.conf--------
default-cache-ttl 7200
---------------------------------------
And (again) the version of gpg components:
gpg-agent  2.1.9
libgcrypt    1.6.4
gpg           1.4.19
gpg           2 2.1.9


Sincerely,
王文鑫
Wenxin Wang
Department of Electronic Engineering,
Tsinghua University,
Beijing 100084, P. R. China
(+86)18811369901
Email：wangwx12 at mails.tsinghua.edu.cn