Previous issues with Pro Tools 11 and "Dynamic Plug-in Processing" have been resolved in updates to Pro Tools. Please make sure you have the latest version of Pro Tools 11 if this check box still affects your audio negatively.
If you are finding that Pro Tools has trouble playing back, recording, or having any normal playhead function, or generates error messages such as "Unable to Initialize ASIO Device Focusrite USB 2.0 Audio" you may want to try an alternate driver.
First go to Control Panel > System > Device Manager > Sound Video and Game Controllers > Right click your Scarlett > Properties > Driver Tab.
Is the version listed here 2.5.X.X?
If so please try one of our beta 3.X series drivers.
Please see our Beta Site and choose either Scarlett MixControl or Focusrite USB 2 Drivers if you have a unit that does not use MixControl
If you are still having trouble you may have a different issue, not related to drivers. Please contact Tech Support.