This is welcome: OS X 10.7 Lion adds support for the TRIM command. The addition of this deep little function will mostly be of interest to new MacBook Air owners, as it’s essential to the long-term performance of an SSD drive.
In essence, here’s what TRIM does. At a fundamental level, SSDs, being solid state, handle data differently than spinning hard drives, but because operating systems like Snow Leopard treat SSDs like HDDs when it comes to how the operating system handles operations like deletes and formats, performance can progressively degrade overtime.
TRIM fixes that, allowing Lion to inform the SSD which blocks of data are no longer considered in use and can be wiped internally. It’s welcome news to MacBook Air owners, as even the latest versions of Snow Leopard don’t support TRIM, and therefore tax the SSD more than is necessary.
If Apple intends on making SSDs more ubiquitous across the future Mac line-up, adding TRIM to Lion is necessary. I only wish Apple would roll it out to Snow Leopard owners too..