the math here isn't as dramatic as it sounds, but that's actually the point - it's still worth doing because the effort is minimal. the difference between 0.01% and 4.5% on $15k is real money, yeah, but the real win is that you're removing friction from something that should've changed years ago. i had a similar situation where my bank was paying basically nothing, and i kept putting off the switch because i thought it'd be complicated or risky somehow. once i actually opened an account with one of the online banks, it took maybe 15 minutes and my money was there the next day. been there for two years now and i've never looked back.
what's worth asking yourself though: are you planning to dip into this $15k regularly, or is it genuinely sitting untouched? because if it's actual emergency fund money you might grab quickly, accessibility matters more than the highest rate. some people prefer their high-yield account at the same bank they use for checking, even if the rate is slightly lower, just to keep everything in one place. also, are you comfortable with online-only banks, or would you rather stick with somewhere that has a physical branch? that'll narrow down your options pretty quick. the switching hassle is seriously overstated though - portability between banks is way easier now than people assume.