A new setting is available in the install tool – dbClientCompress. When enabled, it compresses the communication with the MySQL database, saving network bandwidth, but costing CPU time. This is a useful setting for cases when MySQL and PHP application are on different hosts.
More info:
RFC: #7059: Improve database performance for external database host
http://bugs.typo3.org/view.php?id=7059
http://www.mysqlperformanceblog.com/2007/12/20/large-result-sets-vs-compression-protocol/