DLN.
BootOptimizer

Fast Boot Optimizer Agent

Your Rails app doesn't need to take 15 seconds to boot. This agent optimizes gem loading, autoloading, and initialization. Faster boot means faster development cycles and quicker CI runs.

Here's the Frustrating Part

Slow boot times compound into massive productivity losses. Every day. And most teams just accept it:

  • "Rails console takes forever" — so developers avoid using it, even when it's the right tool
  • "Running one test takes 30 seconds" — most of that is boot time, not the actual test
  • "CI is slow" — every parallel worker boots the full app, multiplying the waste
  • "Spring keeps breaking" — preloaders add complexity and cause weird bugs

The result? Developers batch their work to avoid reboots. Context switches take longer. The feedback loop gets slower. And everyone just accepts it as "the Rails tax."

How the Agent Works

Five steps. Measurable results at each one. No guesswork.

1

Baseline Measurement

First, we measure where you are. You can't optimize what you don't measure.

  • → Measures boot time: time bundle exec rails runner "puts 'booted'"
  • → Profiles with Bootsnap logging enabled
  • → Runs derailed bundle:mem to identify heavy gems
2

Gem Loading Optimization

Most gems don't need to load at boot time. But by default, they all do.

  • → Identifies gems that can use require: false
  • → Moves development-only gems to proper group
  • → Lazy loads gems only when actually used
3

Initializer Optimization

Initializers are sneaky. Some run expensive operations that don't need to happen at boot.

  • → Identifies slow initializers using profiling
  • → Moves heavy setup to after_initialize callbacks
  • → Defers external API connections until first use
4

Bootsnap Configuration

Bootsnap is powerful, but it needs to be configured correctly. Most apps aren't.

  • → Verifies bootsnap/setup is loaded early in boot.rb
  • → Configures appropriate cache paths
  • → Ensures cache is persisted correctly in CI
5

Validation & Results

No guessing. You see the improvement in black and white.

  • → Measures boot time after each change
  • → Verifies application behavior is unchanged
  • → PR shows before/after boot times with percentages.

Common Optimizations

These are the patterns I see most often. Simple changes, big impact.

Lazy Load Gems

Many gems don't need to load at boot.

gem "awesome_print", require: false

Defer Initializers

Heavy setup can wait until after boot.

config.after_initialize { heavy_setup }

Proper Gem Groups

Dev tools shouldn't load in production.

group :development { gem "pry" }

Bootsnap Caching

Cache compiled code for faster loads.

require "bootsnap/setup"

Safety Guarantees

I know what you're thinking: "What if something breaks?" Here's why it won't.

Behavior Preserved

Optimizations don't change how your app works. Just when things load.

Measured Improvements

Every change is measured. No optimization without proof.

Test Suite Validation

Full test suite runs after optimization to catch any issues.

Incremental Changes

Each optimization is a separate commit. Easy to revert if needed.

Production Safe

Works in all environments. No dev-only tricks.

Documentation

Every optimization is explained so your team understands the changes.

Let Me Be Clear About What This Isn't

  • ✗ Not Spring or preloaders. We fix the actual boot, not hide it with caching that causes weird bugs.
  • ✗ Not removing gems. Optimizes loading, keeps all functionality intact.
  • ✗ Not guesswork. Every optimization is measured and validated.
  • ✗ Not dev-only. Improvements apply to all environments including production.

What You Can Expect

Real numbers from real codebases. Your results depend on how bloated your boot is.

40%
faster boot time
2x
faster test startup
Fast
console & runner commands

Ready to Stop Waiting for Rails?

Start with a $1,500 audit. You'll get a boot time profile showing exactly what's slow and a plan for optimization.

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