CPU (i7) experiencing severe throttling

[AZGrove]

For a while, I've experienced throttling during most operation of my W541 w/ an i7-4810MQ CPU. I've had the laptop for five years during which I haven't noticed a serious decline in performance, but it does seem like it's less snappy than an i7 at 2.80 GHz should be. So I decided to run some benchmarks and graph the data to see if there's anything to find.

I ran Cinebench R15 single-core and multi-core tests, in addition to the GPU test and general use during a normal workday. Graphs are here: https://imgur.com/a/Wq9aRzu It's pretty clearly throttling during almost outside of just idling. During my workday, the laptop throttled all CPU cores for close to 25% of the day. Everything was monitored with HWInfo64.

Are there any suggestions for things to check? It's nothing unbearable, but I guess I expect to spend most of the time running at the CPU's advertised speed. One note: I am planning to purchase new thermal paste and afterwards to run the same tests.

[RealBlackStuff]

I think fresh thermal paste (preferably Kryonaut) should solve the problem.
Definitely so if you haven't refreshed it in over 5 years!

[AZGrove]

Okay, I purchased some of the good stuff (Kryonaut) and I'll update once I'm able to apply it.

Any thoughts on why I have a 20°C spread in core temps?

[RealBlackStuff]

Yup, only a part of the CPU surface (enough to cool one core a bit) still has some usable paste on it.

[AZGrove]

Oh, that makes perfect sense! Thank you for your help; I'll post results when I've applied the thermal paste and go from there.