I can't think of any impact to the basic RADIUS functionality disabling the Profiling Service on the PSNs would have, but losing visibility of the types of endpoints on your network would be crippling the functionality of ISE. This would follow the adage 'you can't secure what you can't see'. You also would not be able to use features like Posture or BYOD in future as ISE would not know what type of client provisioning was needed.
If you're using the supported ISE CPU/Memory specs as per cs.co/ise-scale, there should be no concerns regarding CPU/Memory usage. If you're not using those defined specs (including reservation of memory resources for VMs), any performance issues you might experience would not be supported by TAC, which is taking a pretty big risk.
If you are using the supported specs and experiencing CPU/Memory utilisation issues, there may be an underlying issue that requires investigation by TAC.