Lesson learned: when they say "data binding", they're not kidding.

complaining_about_angular.js

/*
 TLDR: I bound expensive filtering to the template and it
 was run too often. After moving filtering to the controller
 it's much faster.
*/

/*
 So what happened with those slow filters?
 
 I started with debounce like we discussed, but this gave only
 a slight performance improvement:
*/

    $scope.$watch("queryWord", _.debounce(function (id) {
      $scope.$apply(function(){ applyQuery(); })
    }, 300));

    var applyQuery = function() {
      $scope.textQuery.word = $scope.queryWord;
    }
    
/*
  here `queryWord` is the ng-model for the search input field,
  and `$scope.textQuery.word` is passed to the filter. I realized
  that the above code only debounces the input, while in my
  template I have lines like:
*/

<span class="nav-counter">{{countWith($parent.prefilteredExceptCharacteristics, 'stove_characteristics', chstic.slug)}}</span>

/* 
  Anything inside double curly braces is refreshed with every
  digest cycle, so `countWith` was being called with each
  keypress (and other events!). By interpolating a filter in the
  template I was re-filtering my data 10^4 times or more for
  each event.

  I moved the filtering into the controller (see SO link below),
  storing the output of each filter on the scope. Binding the
  stored output to the scope, the line above becomes:
*/

<span class="nav-counter">{{chstic.filterCount}}</span>

/*
  With a `$scope.$watch()` on the search text
  input and checkbox filters, each `filterCount`
  is only updated when the search critera change.

  Here's the result: http://catalog.cleancookstoves.org/#/stoves
  (I know the load speed is still too slow, but that's a 
  separate issue)
  
  It's fast enough now that debounce isn't necessary, but I
  left in a 250ms delay on the text input because I think
  it feels better. There's no delay on the check boxes.

  Assorted posts I found helpful:
  http://www.aaron-gray.com/delaying-the-digest-cycle-in-angularjs/ (front page of Hacker News 9/18/14!)
  http://www.sitepoint.com/understanding-angulars-apply-digest/
  http://stackoverflow.com/questions/17656397/angular-js-scaling-performance
  http://stackoverflow.com/questions/21088845/can-i-debounce-or-throttle-a-watched-input-in-angularjs-using-lodash
  http://tech.small-improvements.com/2013/09/10/angularjs-performance-with-large-lists/
  http://stackoverflow.com/questions/14302267/how-to-use-a-filter-in-a-controller
*/