Another minor ones: 
1. If I click on the background with the mouse so the input lose the focus, I cannot use the tab key to bring back the focus on any of the input elements (in Firefox)<p>2. Cannot use Ctrl + mouse wheel to Zoom the page, but Ctrl + &quot;+&quot; works.<p>3. The dropdown list opens using any of the mouse buttons not just the left mouse (should not open on right click or middle click)<p>4. Cannot select the data in the list with mouse (but can select whole page text with Ctrl + A)<p>Also it&#x27;s strange that you are talking about fast load time but I see the opposite: 660KB loaded in 4.5 seconds for the inital page load.<p>Some performance tips:<p>It should be obvious: use HTTP compression, a quick check shows: the total size could be reduced to 27% ! of the current one. Maybe your custom server (&quot;Elevate Web Builder Web Server&quot;) doesn&#x27;t support it yet? This could help with the HTML and JS load times.<p>In the case of the countries JSON it&#x27;s not the transfer size that is slow but the response time of the server: 600ms for a 8KB JSON is not so fast especially if the data is not changing and easily cachable.<p>If it&#x27;s a single-page app then you could embed the JS in the the HTML so all the data comes in one continuous request, and if even the initial JSON data (for the countries) is included then additional more than 1 second can be saved that is currently there between page loaded and starting to load that JSON.<p>Also loading big dataset by selecting United States from the dropdown freezes the browser and Firefox shows the unresponsive script warning (maxgridtext.js). There could be some processing in the JS that may not be necessary to do for the whole dataset but do it only on the visible part of it or it could be done on the server.<p>I post this because I see you care about the UX and performance and I hope it helps you a little.