Premature Optimization: A Software Developer’s Worst Nightmare

Premature optimization is the root of all evil

Donald Knuth, The Art of Computer Programming

Have you ever found yourself obsessing over a single line of code, trying to squeeze out every last drop of performance? Have you ever spent hours optimizing a function that turns out to be called only once in a blue moon? Congratulations, you are suffering from premature optimization syndrome.

What is Premature Optimization, Anyway?

Premature optimization is the tendency to focus on performance too early in the development process. It’s the misguided belief that optimizing every little detail will somehow magically make your code run faster, when in fact it often has little impact on performance.

This is more common among mid-developers, as they reach a point where they know much more than a junior technically, but are still missing the business perspective of their code.

The Costs of Premature Optimization

Premature optimization can have a number of negative consequences, including:

• Increased development time: When you’re constantly tweaking and optimizing your code, you’re not focusing on getting to the solution fast.
• Reduced code maintainability: Code that’s overly optimized can be difficult to read and understand, making it harder to maintain in the long run.
• Decreased team morale and confusion: Spending hours obsessing over a single line of code can be demoralizing, and can lead to burnout and team dysfunction, as well as being confusing for junior developers.
  I remember being a junior developer and seeing a debate during code review on whether function declarations are faster than function expressions (this was a B2B app)… Seriously. At the time, I thought this was very important, which I believe is the worst part of it.

Micro vs. Macro Optimizations

You can work on micro and macro optimizations. Micro optimizations are focused on optimizing individual lines of code, while macro optimizations are focused on optimizing the overall design and architecture of your code.

While micro-optimizations can be tempting, they often have little impact on performance and can distract from more important issues. Instead, focus on macro optimizations, such as:

• Choosing the right data structures and algorithms
• Using design patterns and best practices

The Dangers of Micro Optimizations

Unless you are working on high-performance code like game engines or scientific simulations, micro-optimizations can be dangerous for a number of reasons:

• They can lead to overcomplicated code: When you’re focusing on optimizing individual lines of code, you can end up with code that’s difficult to read and maintain.

function f(x,y){for(let z=0,z=x*y;x>=0;)z-=--x*y;return z;}

// Code reviewer comments: What are you, a minifier?

• They can be a waste of time: Spending hours optimizing a single expression might make you feel productive, but it’s often not the most valuable use of your time.
• They can distract from more important issues: Instead of focusing on micro-optimizations, focus on building features and fixing bugs. You can always optimize later if needed.

The Importance of Profiling and Measuring Performance

Before you start optimizing, it’s important to measure and profile your code to identify the real bottlenecks. This can help you prioritize your optimization efforts, and avoid wasting time on optimizations that won’t have a significant impact.

Some tools for measuring and profiling performance include:

• Profiling tools built into your programming language or IDE
• Third-party profiling tools, such as New Relic, AppDynamics, Sentry, Firebase, etc.
• Logging and monitoring tools, such as ELK or Splunk

Strategies for Avoiding Premature Optimization

So how do you avoid premature optimization? Here are some strategies:

• Focus on functionality first: Don’t worry about optimizing until your code is working as intended.
• Wait until performance problems arise: Don’t optimize unless you’re actually experiencing performance problems.
• Use profiling and measurement tools: Use tools like profilers to identify performance bottlenecks before you start optimizing.

Putting Things in Perspective

Facebook was initially built in PHP, with an extremely simple architecture. The focus was on shipping the solution fast, and rightfully so. Do you think they worried about whether using ++i was faster than using i++?

Spoiler: No.

So stop making your code faster, and start shipping your products faster.

As always, let me know if you have any comments and I’ll gladly see to them ASAP!