JSFiddle - React, Tailwind, and code Playground

HTML

<p>I want this to update to 35 then 45 <input data-bind='value: comp1' /></p> 
    <p>I want this to update to 22 then 45 <input data-bind='value: comp2' /></p>

JavaScript

var ViewModel = function() {
  var self = this;
  self.obs1 = ko.observable(10);
  self.obs2 = ko.observable(2);

  //I want this computed to behave normally
  self.comp1 = ko.computed(function() {
    return self.obs1() + self.obs2();
  }, this);

  //Possible solution?
  self.obs2DelayComp = ko.computed(function() {
    return self.obs2();
  }).extend({ rateLimit: 3001 });
  
  //I want this computed to trigger on obs1 update but ignore updates to obs2
  self.comp2 = ko.computed(function() {
    return self.obs1() + self.obs2DelayComp();
  }, this);

  setTimeout(function() {
    self.obs1(20);
    self.obs2(15);    
  }, 1000);
  
  setTimeout(function() {
    self.obs1(30);
  }, 3000);
};
 
ko.applyBindings(new ViewModel());