Performance improvement from adding caching when rendering mustache partials for GOV.UK search results

benchmark.rb

$:.unshift "lib"

require "mustache"
require "benchmark/ips"

BASE_TEMPLATE = <<end_of_template
<h2>Names</h2>
{{#names}}
  {{> user}}
{{/names}}
end_of_template

PARTIAL_TEMPLATE = '''
<li{{#external}} class="external"{{/external}}>
  <h3><a href="{{link}}" {{#external}}rel="external"{{/external}}>{{title}}</a></h3>

  {{#debug_score}}
    <p class="debug-link">
      {{link}}
    </p>
    <p class="debug-info">
      <span>Score: {{es_score}}</span>
      <span>Format: {{#government}}government{{/government}} {{format}}</span>
    </p>
  {{/debug_score}}

  {{#external}}
    <p class="meta">
      <span class="visuallyhidden">Part of </span>
      <span class="url">{{ display_link }}</span>
    </p>
  {{/external}}

  {{#section}}
    <p class="meta crumbtrail">
      <span class="visuallyhidden">Part of </span>
      <span class="section">{{formatted_section_name}}</span>
      {{#formatted_subsection_name}}
        <span class="visuallyhidden">, </span>
        <span class="subsection">{{ formatted_subsection_name }}</span>
      {{/formatted_subsection_name}}
      {{#formatted_subsubsection_name}}
        <span class="visuallyhidden">, </span>
        <span class="subsubsection">{{ formatted_subsubsection_name }}</span>
      {{/formatted_subsubsection_name}}
    </p>
  {{/section}}

  {{#metadata_any?}}
    <ul class="attributes">
      {{#metadata}}
        <li> {{{.}}} </li>
      {{/metadata}}
    </ul>
  {{/metadata_any?}}

  {{#historic?}}
    {{#government_name}}
    <p class="historic">
      First published during the {{government_name}}
    </p>
    {{/government_name}}
  {{/historic?}}

  <p>{{description}}</p>

  {{#sections_present?}}
    <ul class="sections">
      {{#sections}}
        <li><a href="{{link}}#{{hash}}">{{title}}</a></li>
      {{/sections}}
    </ul>
  {{/sections_present?}}

  {{#examples_present?}}
    <ul class="examples">
      {{#examples}}
        <li>
          <h4><a href="{{link}}">{{title}}</a></h4>
          <p>{{description}}</p>
        </li>
      {{/examples}}

      {{#suggested_filter_present?}}
        <li>
          <h4 class="see-all"><a href="{{suggested_filter_link}}">{{suggested_filter_title}}</a><h4>
        </li>
      {{/suggested_filter_present?}}
    </ul>
  {{/examples_present?}}

  {{^examples_present?}}
    {{#suggested_filter_present?}}
      <h4 class="see-all"><a href="{{suggested_filter_link}}">{{suggested_filter_title}}</a><h4>
    {{/suggested_filter_present?}}
  {{/examples_present?}}
</li>
'''

one_name = [
  {name: "Charlie Chaplin"},
]

data_10 = {
  names: one_name * 10,
}

data_100 = {
  names: one_name * 100,
}

data_1000 = {
  names: one_name * 1000,
}

class Custom < Mustache
  def partial(name)
    PARTIAL_TEMPLATE
  end
end

mustache = Custom.new
mustache.template = BASE_TEMPLATE

Benchmark.ips do |x|
  x.time = 20

  x.report("render list of 10") do
    mustache.render(data_10)
  end

  x.report("render list of 100") do
    mustache.render(data_100)
  end

  x.report("render list of 1000") do
    mustache.render(data_1000)
  end
end

out-after.txt

Calculating -------------------------------------
   render list of 10    69.000  i/100ms
  render list of 100     7.000  i/100ms
 render list of 1000     1.000  i/100ms
-------------------------------------------------
   render list of 10    706.772  (± 4.2%) i/s -     14.145k
  render list of 100     70.872  (± 1.4%) i/s -      1.421k
 render list of 1000      6.986  (± 0.0%) i/s -    140.000

out-before.txt

Calculating -------------------------------------
   render list of 10     1.000  i/100ms
  render list of 100     1.000  i/100ms
 render list of 1000     1.000  i/100ms
-------------------------------------------------
   render list of 10     11.939  (± 8.4%) i/s -    236.000
  render list of 100      1.220  (± 0.0%) i/s -     25.000
 render list of 1000      0.123  (± 0.0%) i/s -      3.000  in  24.305407s