WordPress updates, like Core-, plugin- and themes, sometimes fail because of enabled PHP opcode caches. Popular PHP opcode caches are OPcache, WinCache and APC. Flushing these opcode caches first eases the WordPress update process. And here is a Must Use Plugin to flush OPcache cache …
As the title says, this is a WordPress post with a comma separated tag. This is done using a WordPress filter, are you interested in the code?
Optimize WordPress MySQL tables through Cron, behind the scenes provides and describes a plugin to regularly optimize your MySQL database tables, to improve WordPress performance.