What browser you are using. I experience this slow loading before on my Firefox and to my chrome that's still not updated. FTX website is indeed very heavy to load due to the amount of data processing on there exchange since they have various of product offered. You will really experience slow loading if you have low specs PC or slow Internet. FTX is much heavier to load compared to Binance based on my experience that's why I'm avoiding there exchange as much as possible.
Judging what he writes on the subject he has a problem with their application, probably on a mobile device. I don't he uses a browser on there.
I had similar problems when my battery was very bad or on a low level. Also, poor internet connection can cause such a problem.