I tried with Ctrl+ZIRKUMFLEX / Shift+Ctrl+ZIRKUMFLEX with the same effect.
After reinstall beta 3 I see only a slight delay using Ctrl+ZIRKUMFLEX or Shift+Ctrl+ZIRKUMFLEX. But I was surprised that Ctrl+Tab and Shift+Ctrl+Tab works as expected without settings in Key Configuration. And 2. surprise - this works without any notable delay.
Ok, so I should not configure Key for myself and use the defaults.