If you don't want YUM throttle your whole internet connection during an install/update process, use the parameter below on /etc/yum.conf:
# Limit download bandwidth (bytes/sec): throttle=256k
If the line does not exist, create it at the end of file. You can also use one of the available suffixes (k, M or G) to express kilobytes, Megabytes or GigaBytes.
On the other hand, if you do want to use all available bandwidth, comment/remove it from the file.