Please bear in mind that - as the society has already pointed out - this was originally intended as a printed document. It may help understand where things fit or don’t fit.
I’m reading between the lines, but I expect that the original slow response was due to the size of the underlying pdf file. pdfs sent to the printers have to be much higher resolution than ones intended for rendering on a screen. But I’m guessing.
Anyway, now that’s addressed, it loads and runs perfectly. Page turns happen immediately. So a suggestion would be that if you are still having delays - and you don’t have a problematic internet connection - then either your computer is too old/slow/overloaded, and it may be time to take that in hand.
Apps.? Already well covered by others. Yesterday’s approach to a problem that’s been solved.
For the record, the reader software initially installed as silent, and I had to switch the sound on to see what the comments about page turn noises were about. So all in all, I like it a lot.