Another possibility is if the OCZ Agility drive has been mounted with the "discard" flag set (look in /proc/mounts for "discard").

Despite my best advice at the time, other kernel devs moved to make "discard" (aka. "on the fly TRIM") the default setting in some distros, even though many/most drives of the time could be rather slow at doing TRIM, including the Agility-3 series.

My main notebook/system here runs entirely from an Agility-3 drive, and never stalls or stutters. But I ensure it never gets mounted with a "discard" flag set, preferring instead to run my own "wiper.sh" script once every few weeks to catch up on TRIM operations. The newer "fstrim" utility does the same sort of thing these days.