"Disable or throttle back Tracker indexing
Installed and running by default on Ubuntu desktops, Tracker is an
actually handy search tool that's placed, Spotlight-style, in the
upper-right taskbar, giving you quick access to files and folders.
The only catch is that Tracker eats up a good bit of processor
power to keep itself current, and, depending on how you use your
system, might not be necessary at all. The How-To Geek walks
through the process of scaling back or disabling Tracker entirely.
Looking for a low-power, high-functioning alternative? Try learning
the magic of find."