Internet access slows down dramatically after a certain amount of time online

1. How much memory does your computer have?
2. Browsers these days tend to use up lots of memory.
Check Task Manager Performance tab and possibly in addition open the resource monitor 

Check your OS build, check advanced update settings including  delivery option. Check whether  your system is being accessed to pull updates fromYOUr system.

What is your connection?
Do not open any browser, but instead start a command window inelevatedodeif possible,
Run
netstat -anob | more see what a process has an established connection.

@dovidf
1)
Using procexp.exe may help you.
https://www.download3k.com/Install-Process-Explorer.html having links to:
1. Download3k US => ProcessExplorer.zip
2. Download3k EU => ProcessExplorer.zip
3. Developer Link 1 => ProcessExplorer.zip

2)
C:\Windows\System32\taskmgr.exe
3)
Open cmd.exe as administrator
C:\Windows\System32\NETSTAT.EXE -nato
OR
C:\Windows\System32\NETSTAT.EXE -nato | C:\Windows\System32\find.exe "ESTABLISHED"
Instead of using ESTABLISHED we can check the same replacing ESTABLISHED with:
a. TIME_WAIT
b. LISTENING
4) either using windows r OR at command prompt
C:\Windows\System32\taskkill.exe /f /im firefox.exe
OR
C:\Windows\System32\taskkill.exe /f /im chrome.exe
OR
related process which you feel to kill.
5)
Examples of using tasklist at https://www.windows-commandline.com/tasklist-command
C:\Windows\System32\tasklist.exe /fi "username eq %USERNAME%"
OR using more inside C:\Windows\System32\cmd.exe
C:\Windows\System32\tasklist.exe /fi "username eq %USERNAME%" | more

>> The chrome browser dies due to a page timeout on various websites. Firefox lasts a little longer but ultimately dies out. I've checked task manager and i've found some reporting high power usage. Malwarebytes reports this often. What could be the cause of this problem
Hence written comment related to Windows.

Dr. Klahn,

"Then check the Startup group to see what else got slipped into the system under cover of darkness.

There are things which can be done to Firefox to cut its CPU and network loading back, but pick the low hanging fruit first.

Finally:  You didn't mention what kind of internet connection you have.  If it's a nonstandard connection such as a tethered phone or a wireless modem, the service provider can throttle your connection and this is commonly done after reaching a monthly transfer limit.  They don't shut off your service, they just make it unusably slow. "

I checked the startup group and knocked out a couple of tasks which were unnecesary and things improved a lot.

Both Chrome and Firefox are affected with Chrome being affected more severely and dying. and marked as suspended in task manager.

I have a direct standard connection from Verizon and my computer is  directly wired to the router

I see a task Checkpoint Sandblast Agent which I never installed myself directly. I thinki it would be safe to stop it from starting

Arnold,

"Check your OS build, check advanced update settings including  delivery option. Check whether  your system is being accessed to pull updates fromYOUr system.

What is your connection?
Do not open any browser, but instead start a command window inelevatedodeif possible,
Run
netstat -anob | more see what a process has an established connection."

I have a standard up to date installation of Windows 10 build 1909. What are we trying to find with the netstat?

Murugesan N,

I can kill tasks directly from task manager. Did you intend something else?

Whether you have extraneous network feeds pulling down your feed. Double check whether your update option includes that your system can server as update respository from which other computers on the LAN or through out can use.

In short, is your system an MS windows 10 update repository?

>> kill tasks directly from task manager
yes either manual
or automation using related batch file since I always face using firefox before 1 year.
Uninstalled due to that.
Thank you for making this query at resolved state.