On “Reign of Terror” — last year’s sophomore sledgehammer from New York noise-pop duo Sleigh Bells — composer and multi-instrumentalist Derek Miller was reeling from the shock of two tragedies: the sudden death of his father and his mother’s cancer diagnosis. The album revealed the despair. But last week, he and vocalist partner Alexis Krauss returned with the rapid follow-up “Bitter Rivals,” which feels sunny and optimistic — relatively speaking. Buttressed by handclap percussion, dog-bark samples and acoustic guitars amped past 11, songs such as “Sugarcane,” “Tiger Kit” and the jubilant “Young Legends” still split skulls. But they apply a comfy Band-Aid afterwards.

How is your mom? She’s great. She’s been in remission for over two years now. I mean, she’ll never fully be in the clear. But everybody back home in Florida is happy and healthy, and everything is just exponentially better than it ever has been. So I’m thrilled — I could not be happier, to be honest.

Dealing with death seems to flip a switch on creativity. You realize that we don’t have forever, right? Exactly. I’m more interested in talking about LP 4, and this record’s [just] out. I know that sounds obnoxious, but that’s just the rate at which I work. I just don’t waste time, and I don’t do anything else. I live and breathe this band. And it’s getting more and more intense for me — it’s not slowing down, the output. And the more Alexis and I work together, the more comfortable we get. We just finished this record, and you’re supposed to feel taxed and wrung out when you finish a record. But I feel totally refreshed.

You predicted “Bitter Rivals” the last time we talked. You said you were planning on putting Alexis upfront in the mix. I was totally hands-off this time around. I let Alexis handle all the vocal duties, and it’s sort of like — for the first time — we have very, very real chemistry. We don’t really second-guess ourselves — we just plow forward. So really, this record is the story of me coming out of that black hole that I fell into after my dad died and my mom fell ill. I just finally dealt with it. It took almost four years, but I did it.

What tools did you employ? Honestly — and it changed my life — I started boxing. I started training to box last February, and I’ve been going four days a week ever since. Progress is very slow, and you barely notice it, but every three or four months, you realize you’ve taken a step. It feels like when I learned how to play guitar at just 10 or 11!

IF YOU GO

Treasure Island Music Festival

When: Noon to 10:30 p.m. Saturday-Sunday

Tickets: $85 to $275, $40-$70 for parking only

Contact: www.treasureislandfestival.com, www.ticketmaster.com

Note: Free shuttles from the Bill Graham Civic Auditorium, 99 Grove St., S.F., begin at 11 a.m. both days; a limited number of passes for parking on the island may be purchased online

THE LINEUP

SATURDAY

Bridge Stage

Atoms for Peace, 9:25 p.m.

Little Dragon, 7:40 p.m.

Major Lazer, 5:55 p.m.

Disclosure, 4:20 p.m.

Danny Brown, 2:45 p.m.

Adult., 1:15 p.m.

Giraffage, noon

Tunnel Stage

Phantogram, 8:35 p.m.

Holy Ghost!, 6:50 p.m.

DJ Falcon, 5:10 p.m.

Poolside, 3:35 p.m.

Robert DeLong, 2 p.m.

Antwon, 12:40 p.m.

Silent Frisco

Vin Sol, 9 p.m.

Motion Potion, 7 p.m.

DJ Dials, 5 p.m.

Matt Haze, 2:30 p.m.

Shouts!, noon

SUNDAY

Bridge Stage

Beck, 9:20 p.m.

Animal Collective, 7:40 p.m.

James Blake, 6 p.m.

STRFKR, 4:20

Lord Huron, 2:50 p.m.

Palma Violets, 1:25 p.m.

Deep Sea Diver, noon

Tunnel Stage

Sleigh Bells, 8:30 p.m.

Japandroids, 6:50 p.m.

Real Estate, 5:10 p.m.

HAIM, 3:35 p.m.

Cayucas, 2:05 p.m.

IO Echo, 12:40 p.m.

Silent Frisco

Lukeino, 8 p.m.

Mancub, 6 p.m.

8Ball, 4 p.m.

NonStop Bhangra, 2 p.m.

Steffi Graff, noon