Anonymous User wrote:1. Should I just put that $25,000 from my checking account toward loans? Into my Vanguard? Do something else with it?
2. Should I slow down my repayment and just stockpile money in other accounts, making lower loan payments given my super low interest rate?
It depends on what you want. The highest return would generally be to (1) pay minimum on the loan, (2) max retirement accounts, then (3) dump everything else into a taxable brokerage account. The only obvious thing you're missing from your post (maybe you do it, maybe you don't) is maxing out your backdoor Roth. Depending on how you split things with your SO, consider maxing his/her 401k/IRA too (or not, if you're not there yet).
But if you really psychologically value being debt-free, then it may be worth trading a lower return for that benefit. That's your call and nobody here can answer that for you. Personally I lean towards getting the higher return, in which case I would invest everything beyond what you need for your efund/401k/IRA in a brokerage account. Higher return in the long run and you can always put that money into the loan down the road if you really want to (even though the risk is that you've lost money in the interim). No matter what you do, I would not leave the 25k sitting in a checking account (either put it in a brokerage to invest long term, put in savings to invest short term, or put it into loans to save on interest).
If you do decide to pay it off early, don't forget you're likely coming close to the 48 month window for the FRB rebate. It's probably only a few grand (2% of original balance), but it does help cover at least some the cost of foregoing the higher return.