for(;;);
It looks funny but if you think about how a for loop works you can see how this basically turns into a looping nop instruction.
That said since you are dealing with an interpreted language I'm not sure if this would actually turn into an infinitely looping nop instruction like it would in c.
This makes it so that other threads may be delayed in getting access to processor time giving you a slow response and also doesn't let the chip go into a power saving mode.
It shouldn't delay any other threads as the processor is always doing "something" nop's or otherwise, but you're correct that it will increase power consumption.
Edit: This statement is unverifiably vauge