Depending on the speed of the internet and the device we use. I experience it myself if the capacity of the device used and the internet quickly does not affect the game we play even though in browsers like Chrome has a number of tabs that are opened more than one.
Playing the type of gambling game in mobile using Chrome does not get obstacles like slow obstacles. Using the default mobile internet browser is also not slow and I often do it. Why open the tab more than one if only one tab is needed.
Usually we like to search multiple things online at the same time meanwhile we can make bets as well which is why someone open more than one tab. Basically I have around 5 to 6 tabs open while I am browsing.
Chrome, Opera or any browser use more or less of similar resources of our CPU and if you see chrome is taking more space of your RAM then it's one of the usual virus attacks which is very common and can be removed with simple changes in the settings. Casino sites are optimised and can work with less internet speed as well.