Will relocating my Central AC intake improve performance?
Most forced-air HVAC systems in Residential are both heating and cooling.

What might be efficient in the summer will not be efficient in the winter.

So, where do you live and which do you use more?

If you live in Arizona you optimize for cooling but if you live in Minnesota you optimize for heating. Then you just deal with a less efficient system in the opposite season.

Re-routing your ductwork may be much less cost efficient than simply buying a newer AC unit with a higher SEER rating.

Make sure you think this all the way through before pulling the trigger on anything.

Good luck!