Let me contribute to this. In addition to what you had explained, it is off truly, and it does not happen on my end. And it might not be the internet connection most times, it might be the spec/capacity of the system he is using to play it. There are some systems that would also have good spec/capacity but the player must have overstressed the system by opening many tabs and performing other background functions that are causing some heavier sites to have loading/responsive issues. But this mostly stops after it has successfully loaded.
I do not think that a casino would really require such a spec, I mean I play on my phone and there are not that many computers with worse spec than my phone, there must be some of course but not many, maybe 1% of the computers made in the last 10+ years would be worse than my phone.
So, I feel like internet connection is the number one suspect here, delay is something regarding internet connection and ping levels being high. If the ping is bad then you are going to get a delay on these things. Like for example a very fast internet speed, but a bad ping could result with you starting a video very late, but then watching it with no buffering.
I was referring to those possibilities in addition to the internet connection initially indicated by some users. And as a matter of fact, the spec of phones and laptops matters a lot to the applications we are opening them with. It is until the OP explains in detail that we can fully know the kind of phone and laptop he/she uses. It might be a low-spec gadget since I had a similar experience some years back, to the extent that the gadget will be so slow and later shut down the app by itself. Cookies, caches and dump files can add up too, especially on laptops.
We often ignore this even with high-spec gadgets, but it could aggravate when they are too much.
