@Pearly : This sounds about normal for a majority of broadband users once the kids have got home from school.
In fairness, it's not something that I suffered with for a few years now since switching to an ISP that is using a hybrid fibre coax implementation based on EuroDOCSIS 3.0, our speeds have remained mostly consistent throughout the day.
I suppose you're on cable as opposed to fiber? Cable service has been notorious for node congestion.
If Bell Fiber is available to you, I highly recommend switching They'll run a new fiber line straight into your house when they set you up.