Why is my HP laptop (Win 10) responding so slowly?

I have a HP laptop with Windows 10 that is two years old.

This has always worked well - until now. Recently, the PC starts up very slowly, hangs constantly and reacts very slowly.

The PC has a valid antivirus program, I have not reinstalled any programs and visited any virus-infected pages.

What could be the reason? And what could you do about it?

Is always difficult to say on the internet easiest way: go into the energy saving settings and adjust "maximum performance" - maybe that helps otherwise. What is the autostart? Are there any unnecessary programs that you can disable? What kind of hard disk, ssd or hdd (or sshd?) And how full is it?

Uhh, that can have 101 reasons. Therefore, a remote diagnosis as you expected is hardly possible.
Usually updates are to blame, even defective hardware would be theor. Possible.

Similar to asking: My car jerking when accelerating, what can that be?

"An antivirus program" is unfortunately as meaningful as "found somewhere on the Internet" and means nothing.
Your calculator might well be affected by malware.

To be on the safe side, you could create a Khttps://support.kaspersky.com/de/viruses/krd2018 on another computer (!) And check your system with it.

Alternatively, let https://de.malwarebytes.com/...bytes.com/ check the computer.

In general, it is also advisable to have a look at the event log to see if there are any errors and / or warnings.