Use yum without downloading or updating its metadata.
By default yum will download and update its metadata.
$ yum list vim-enhanced Loaded plugins: fastestmirror Determining fastest mirrors * base: centos2.hti.pl * extras: centos1.hti.pl * updates: centos2.hti.pl base | 3.6 kB 00:00:00 extras | 2.9 kB 00:00:00 updates | 2.9 kB 00:00:00 (1/4): base/7/x86_64/group_gz | 165 kB 00:00:00 (2/4): extras/7/x86_64/primary_db | 152 kB 00:00:00 (3/4): updates/7/x86_64/primary_db | 1.9 MB 00:00:00 (4/4): base/7/x86_64/primary_db | 6.0 MB 00:00:06 Available Packages vim-enhanced.x86_64 2:7.4.629-6.el7 base
Next time define --cacheonly option to skip that part and run completely from system cache.
$ yum --cacheonly list vim-enhanced Loaded plugins: fastestmirror Installed Packages vim-enhanced.x86_64 2:7.4.629-6.el7 @base
To quickly update cache by hand execute the following command.
$ sudo yum makecache fast Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile * base: ftp.wcss.pl * extras: mirror.mijn.host * updates: tux.rainside.sk base | 3.6 kB 00:00:00 extras | 2.9 kB 00:00:00 updates | 2.9 kB 00:00:00 Metadata Cache Created
Read yum manual page for more information.