Took 6 seconds on a Samsung Galaxy S6, Firefox. I definitely would've closed the tab if I hadn't read this.

The combined size of the concatenated js/css files was 1.7mb before compression. Now, both combined are 366KB respectively.

The load time should be much better now.

Oh, it actually worked? I waited a couple seconds and closed it, assuming it was broken.

Yes, I know. Emphasis on 'working on.' I haven't gotten to optimization yet.

Try it again.

5 seconds browser loading. Then blank screen for about 5 seconds. Then a spinner for about 3 seconds.

No matter how much optimisation you're doing, you're still destroying the progressive loading of HTML pages and the ability for my browser to tell me how my page is loading.

It may be a fun project, but it's not based on sound technical decisions, in my humble opinion.