The Enable Record on Selected Audio/MIDI Track option has nothing to do with an “ultra low latency record mode”, I’ve never heard of this before.
The only thing it does is applying Audio Pre-Record Seconds, meaning that all record enabled Audio tracks will record the input signal in the background in order to keep the last X seconds when you hit Record. But this is done in the RAM, and the stress on CPU is indiscernible.
I think what you describe is the ASIO-Guard that is simply not compatible with real time dependent signals, that is, Instruments that are monitored, either by the monitor button or when it is record enabled, in the case Auto Monitoring While Record-Enabled option is selected (which is by default). There’s no hidden “ultra low latency” mode whatsoever, that’s the very first time I hear that. 
ASIO-Guard only serves to reduce the strain on the CPU, so when it is disabled you just see your real CPU performance… We are all so used to this feature that we think this is the “normal” operating performance, but if ASIO-Guard is turned off completely in the settings, most big projects won’t even play anymore. A lot of people overestimate their CPU capabilities just because there’s many features that help it perform better.