I have attached a test map
The test map contains the lowest interval for the Healing Waves to occur (the use of 0.01 second per interval)
My computer cannot withstand the speed and it lags, veeeeerrryyyy lag, but it doesn't even crash my the warcraft even for 30 seconds (that's long dude, trust me)
What does this test map do ?
For each interval of 0.01 per second, the trigger will picks up any ally unit that is and targets it and healed it by using the default Healing Waves (dummy casts it)
You can press ESC (if your PC is good enough) button to reset all of the unit's HP down to 1% remaining HP and let the healing process occur again
This test map does nothing only to prove that there can be no crash if we use the loop of healing passively.