The amount you save is so much more important than eeking out an extra 1 or even 2% return.
Yep, that should almost be a piece of header text that appears at the top of this subforum.
However, it's worth noting that that advice shifts somewhat over the course of a person's wealth-accumulation stage. It's super-important to remember for someone just starting out, almost to the point where throwing money at anything could be better than putting it off due to fear of making the "wrong" choice. But for someone closer to retirement (or even moreso, *in* retirement), then the returns become more of a factor. Increasing return (or lowering expenses) 1% on a $2M portfolio generates $20k in a year, which could be more than the amount added to the portfolio via savings.
One of my favorite bits of "SAVE EARLY!!!" math comes from Vanguard:
https://personal.vanguard.com/us/content/SiteWide/FlashPgs/SWFlshPwrOfCompContent.jspIn their example, Dawn starts investing at age 25, at $2000/year, but she STOPS adding to the account at age 35 and never puts in another penny.
Dave delays investing until age 35, at $2000/year, and keeps investing for the next 30 years (three times longer than Dawn), until he's 65.
Assuming the same 8% return for both of them, Dawn has $314k at age 65 (even though she only invested $20k), while Dave has only $244k (even though he invested $60k). Even though I totally know the math behind all this stuff, I'm still surprised when I see that result laid out.