WindowServer CPU Usage
Seems like at night when f.lux is active I'm getting high CPU usage from the WindowServer process. Usually over 50% but sometimes into the 80% range. Basically I can't use f.lux when my laptop is not plugged in, or the battery will drain real fast. When I quit f.lux WindowServer drops down into the teens or below.
A few questions: Which OS version? Are you mainly using Chrome? Do you have window transparency on?