How processor intensive is analogWrite?

Hey!
How processor intensive is analogWrite? If for example, you use all your PWM pins in your program, will that hog up a heck of a lot of CPU cycles? I ask because I am trying to use 3 servos and also PWM some leds but am running into trouble when i start to light up my led;s. the servos get a bit 'jittery'. I have given thought to offsetting my led PWM to an attiny. Is this overkill?
Thanks.

PWM is handled by the timers; once setup, there's no processor overhead.

I am trying to use 3 servos and also PWM some leds but am running into trouble when i start to light up my led;s. the servos get a bit 'jittery'.

This is because the servo libiary uses the same timers some of the PWM pins. Nothing to do with the PWM process itself.

Also any code that disables interrupts for some time will disturb servos as they need to be able to get at the interrupt system to work.

Sorry, I should have qualified my answer, "PWM for analogWrite is handled by timer hardware. PWM for servo control (via the Servo library) has an element of software overhead".

Thanks for the swift reply's!

PWM is handled by the timers; once setup, there's no processor overhead.

why is it that we are limited to a limited number of pins if there is no overhead?

This is because the servo libiary uses the same timers some of the PWM pins. Nothing to do with the PWM process itself.

So by simply changing which pin I use for my led's i could circumvent this problem?

why is it that we are limited to a limited number of pins if there is no overhead?

Because only some pins are connected to the timers.

Each of the three timers can control two pins with PWM. These pins are fixed in the hardware of the processor and their is nothing you can do to change it.

So by simply changing which pin I use for my led's i could circumvent this problem?

Maybe, it depends on how many LEDs you have.