When you spend a significant amount of time there it can be a little painful.
If it helps, I have a Tampermonkey • Chrome UserScript I use to make it easier.
It essentially fixes (floats) the navigation on the left and allows each group to be scrolled.

(function() {
'use strict';
$('.col-md-3.schema-nav').css({
'position': 'fixed'
});
$('.schema-nav .row').css({
'height': '300px',
'overflow-y': 'scroll',
'margin-bottom': '15px',
'border-left': '5px solid #ccc',
'background': 'white',
'padding-left': '3px'
});
$('.schema-nav .row h4').css({
'position': 'fixed',
'z-index': '100',
'background': 'white',
'margin-top': '0px',
'width': '15%'
});
$('.schema-nav .row .col-md-12:first-of-type').css({
'margin-top': '40px'
});
$('.schema-nav .row:last-of-type').css({
'height': '75px'
});
$('.col-md-9').css({
'float': 'right'
});
})();
cc: oxana