The most likely thing is that your RAM is relatively small and should be expanded. RAM is often associated with slow processing power of a computer system. So, I will advise that you troubleshoot that as soon as possible.
Well my best guess is that your laptop's RAM is pretty small and your CPU isn't very good at multitasking. Your laptop is probably struggling to keep all your tabs open without having to reload or close any of them and in so doing it's causing your CPU to lag a bit.
A remedy would simply be to not open as many tabs at once, if you're done with one app or tab then close it and don't leave it open in the background. Doing this will probably make your user experience a whole lot better.
I'd also advice that you put your laptop's battery mode on 'high performance' while you're using it, that way there's nothing that's limiting the CPU performance and it's working perfectly well. It could be that the reason why your laptop slows when you open multiple tabs is because there are optimisation options that are active which are limiting CPU performance, so it's worth a try to check if any such setting is on.
I hope this helps
This tends to happen a lot when your RAM(Random Access Memory) is relatively small and should be expanded.
I got the same issue on my PC earlier last month, it's get to slow up my work and operating systems when's I get to open 7tabs on it. So I had to make enquiry about it and I realized that I really need to expanded and upgrade the RAM to carry out operation on it swiftly.
RAM is often associated with slow processing power of a computer system.
So I hope this helps a bit.