Currenty I'm using [Change signature propertiesGeneric Detection Signatures (High/Medium Accuracy)] I want to enable all signature set so I can use all attack signatures. If I enable all of them will there be any performance problems or can I safely enable it?
You can safely enable all of them without worrying about a performance hit. However, you should consider only using those signatures that are applicable to your environment--for example Linux signatures don't make much sense in a Windows environment. If you enable the option to "Detect Server Technologies" you will see suggestions for adding signatures that the system has detected based on traffic observations.
