Optimizing Ruby Code – Small Changes Add up to Big Performance

Ruby offers a lot of great features for manipulating data. If we aren’t careful though, it’s easy to write code that consumes more memory and CPU time than we would expect. Here’s a tip on optimizing Ruby code for better performance.

Consider this locale detection code:

string = params[:country]
 country = COUNTRY_CODE_MAP.detect do |k,v|
     [k.downcase, v.downcase].include? string.downcase
 end

Although it reads nicely, this code has several performance issues:

With a few simple modifications we can greatly reduce the number of operations and new variables used:

string = params[:country]
 country = COUNTRY_CODE_MAP.detect do |k,v|
 k.casecmp(string) == 0 || v.casecmp(string) == 0
 end

In the refactored code we:

1. Don’t create a new array on every iteration.
2. Don’t copy the strings by not using downcase.
3. Only compare to v if k doesn’t match.

Although these differences may seem small on the surface, remember that this code may get run millions of times a day. Also, your collections may grow to sizes that you never imagined! It’s small changes like these that will make huge differences at scale.

Share your tips for optimizing Ruby code for better performanceOptim in the comments below.