How to fix N+1 queries in Prisma + NestJS under high load?

// BAD: N+1
const users = await prisma.user.findMany();
for (const u of users) u.posts = await prisma.post.findMany({ where: { userId: u.id } });

// GOOD
const users = await prisma.user.findMany({
  include: { posts: true },  // or join strategy
  where: { id: { in: userIds } }
});