How Paying Down Technical Debt Can Instantly Boost Development Speed

Definition of Technical Debt

Technical debt is any issue in a codebase that makes required changes harder for developers. Ignoring debt can degrade morale, increase turnover, and slow delivery, while targeted repayment can immediately improve build times, reduce bugs, and accelerate feature rollout.

Case Study 1 – Atalasoft Build System Rewrite

At a .NET‑focused tooling company ( Atalasoft) the build and installer scripts had become a tangled legacy that required constant maintenance. The team allocated one developer for roughly one month to replace the legacy scripts with a modern build system based on contemporary tooling (e.g., MSBuild/NuGet, automated CI pipelines). The rewrite yielded:

CI builds that completed significantly faster (seconds instead of minutes).

A smaller, easier‑to‑modify codebase.

Immediate reduction of reported build‑related bugs because the new system enforced stricter validation.

Full unit‑test coverage of the build logic, eliminating the need to run full builds for every change.

These benefits were realized without jeopardizing the product roadmap, demonstrating that even a modest, time‑boxed rewrite can produce rapid productivity gains.

Case Study 2 – Trello iOS Navigation Over‑Rewrite

When the author joined Trello in 2014, the iOS app had grown to support 6 million users. Apple’s transition from iOS 7 to iOS 8 introduced new presentation controllers that broke the existing navigation code, causing crashes during in‑store demos.

The team responded by designing a custom, non‑standard navigation framework and rewriting the entire navigation stack over several months. In hindsight, the effort was excessive; fixing the specific crash‑inducing paths would have sufficed. The episode reinforces Joel Spolsky’s observation that “reading code is harder than writing it” and that large rewrites often incur unnecessary risk.

Heuristic for Balancing Debt and Value

The author now asks:

“If reducing a specific piece of technical debt can *immediately* improve developer productivity or deliver business value, repay it; otherwise, defer it.”

When debt is so large that it blocks value delivery, the team may consider larger refactors, but only after the immediate‑impact criterion is met.

Continuous Small‑Scale Refactoring

Inspired by Kent Beck’s Extreme Programming and Martin Fowler’s Refactoring, the team adopts a routine of:

Making tiny, behavior‑preserving commits that clean up code.

Writing unit tests for new or changed code to guarantee correctness.

Running a continuous integration (CI) pipeline on every commit.

This approach was applied to a B2B SaaS product, yielding quick wins such as clearer code and faster verification of changes.

iOS MVVM and Internationalization Testing

In the Trello iOS codebase the team introduced a Model‑View‑ViewModel ( MVVM) architecture, enabling view‑logic unit tests. They also added a comprehensive unit‑test suite for internationalization ( i18n) string interpolation and pluralization. Previously, verifying a string required manual navigation through the app; the new tests enumerate expected inputs and outputs and run in under a second, dramatically reducing verification time.

Design System with Abstracted Style Tokens

The team built a design system that centralizes font sizes, colors, and other visual attributes into reusable tokens. By replacing hard‑coded values throughout view controllers with references to these tokens, developers can:

Write UI code that matches the design spec automatically.

Propagate design changes globally by updating a single token definition.

This abstraction improved consistency and reduced the effort required for visual updates.

Practical Guidelines

Visualize debt impact with dashboards to prioritize work.

Allocate short, time‑boxed experiments (e.g., one‑month rewrites) to assess ROI before larger commitments.

Prefer targeted fixes over full rewrites unless the debt completely blocks value delivery.

Link every debt‑repayment effort to a measurable productivity or business outcome.