I can not say anything about the "Potentially unsafe applications" setting since it is off in ESET for me.
But I do have the top 3 also set to aggressive, and since I started using ESET, the only times I got a warning so far is when I downloaded an update for a program that ESET does not completely trust so to speak. For instance, ESET did not allow me to install the latest update from HiBit Uninstaller before it had checked it in the cloud.
As for performance with those three set too aggressive, well for me in my desktop at least, only 10 to 11% of memory is used.