This article teaches how to avoid audio latency:
How to Remove Audio Latency
In short, there's three approaches you can take:
- Export the busy song to an .mp3, then open a new project and record over it (this allows you to record at extremely low latency due to very little CPU strain.. this is most affordable way, too)
- Get an audio interface that provides direct monitoring with a knob, so you can hear your voice instantly within the audio interface itself over the music (but you don't get the benefit of listening to your recording with digital effects)
- Send the audio out to an audio mixer.. this is the way to 100% remove audio latency, and if the mixer offers digital effects, like reverb, you can apply that to make recording a bit easier, without actually recording the digital effects (still record dry).