render_with_sequencer.js

var BLOCKSIZE = 500;
var dataset   = [];  // Assuming, of course, that there's something in here..

var renderActions = [];

for (var i=0; i<dataset.length; i+= BLOCKSIZE) {
  renderActions.push((function(offset) {
    return function(callback) {

      //
      // Perform rendering here using dataset[offset] to start
      //

      setTimeout(callback, 1); // Release control
    }
  })(i)); // 'i' gets pulled into the new scope as 'offset'
}

var sequencer = new Sequencer(renderActions);
sequencer.start();