How to reduce Garageband voice recording delaying/skipping issues?

I just bought a refurbished 13” 2.4 gHz, 4GB RAM MacBook Pro with Focusrite Saffire Pro 14 interface. Using Shure Beta87 microphone. When monitoring the recording, the vocals are crisp and perfect, but on playback I am getting a lot of “delaying”.and catching – hard to describe, but it sounds a bit like autotune, where the vocal track is getting tripped up and holding for a few milliseconds longer than it should. This occurs even if no effects are utilized and AirPort is turned off (as some forums have suggested). Wondering if this is a GB problem or if I need to upgrade to Logic. Again, it doesn’t seem like an interface issue as the quality is great while monitoring, just on playback does it start to “slip.” I’ve also read that you can do the below, but this option is not available on my version of Garageband:

Choose GarageBand > Preferences, click the Audio/MIDI tab, then click the “Maximum number of simultaneous tracks” button in the “Optimize for” section.

Any suggestions would be very much appreciated!