Hello,
Technically, Windowblinds can change the vertical size of titlebar. But, do know Windowblinds can not change specific area only. Which mean, if you load a Windowblinds theme, that have small vertical size titlebar, you will need to load those other part that come with that theme too. You can not really pick and chose which part you allow to change.
But, if you know Skinstudios and willing to mod a theme or create your own theme/skin. That might work.
As for Windows performance while Windowblinds loaded, from my experience, if configured properly, it should be none. There will be some applications that not compatible with Windowblinds which might causing issue. But, those application, can be set to be "Ignore" by Windowblinds. Windowblinds will not skin those application.
Thank you.
Basj,
Stardock Community Assistant.