It has been there for a couple of weeks and doesn't look very deep, but I'm wondering if that might impact how the screen functions. Do I need to consider getting it repaired? Thanks!
Personally, I'd wait.
If it really is just a surface scratch, then it won't be doing any other damage. It won't get worse over time. Save your money.
If it turns out to be damage to the LCD screen itself, then it may gradually get worse & need replacement.
That's the time to decide whether it's worth it.
See Mac Service and Repair for current pricing.
If this is a touchscreen and your touchscreen functionality is suffering or producing phantom clicks then certainly consider getting it repaired.
If the above statement does not apply to you and you're just looking at the screen with your eyes then I would just leave it be. If the crack spiders out into the entire screen and hinders your usage then I would consider a repair. The remedy is a total screen replacement in either situation so why shell out the cash now if it doesn't bother you?
A screen scratch isn't going to affect your CPU performance if that's what you're asking.