Quarter of screen size of 1920x1080 pixels would be 960x540 pixels and using 16bits instead of 32bits may help a little. It's still 1MB per frame so not fast to read and later encode.
16-bit screens look so crappy it is an insult... but it would help if Screen Recorder just dumped screen to HD and encoded it later. At 15/30 fps you could get acceptable results.
Screen Recorder also allows recording smaller area under mouse pointer. This should produce interesting videos, too.