Is there a way to configure the behaviour of cmd + tab to not wait until they get released?
Pressing CMD` cycles through windows of the current App immediately.

No need to release the keys to select the window.

Some of the 3rd party apps listed here might get you the same solution for App switching:
https://superuser.com/questions/193922/is-there-any-program-or-way-to-make-mac-os-xs-tab-behave-like-windows-alt-ta