I think you answered your own question. You have a pinhole leak. The system is under pressure and will continue to leak until it reaches a certain level. The compressor will supply a cooler temp at higher rpms because of this. If your not going to repair the leak, I would suggest disconnecting the compressor as it will only lead to other problems.
In Canada, refrigerant is hard to come by unless you are in the field. Due to the greenhouse gas thing, a certified mechanic cannot "top up" a leaking system, It must be fixed.