Dell tends to shoe-horn in a bunch of crap with their installs...
Is it at least running at Intel spec? ( which is quite probable (Dell was never known for being aggressive in attempting any 'factory overclocking', or running a CPU beyond it's Intel-intended workload, which would likely mean the CPU might jump to 4.10 GHz for a fraction of a second when opening an application, etc., and might even run at 3.7 GHz for 30-60 seconds under multicore workloads, but, the TDP limits should have this clocking itself down to closer to 3.0-3.2 GHz, as it is bu a 65W CPU....)
If a few minutes after bootup, you install HWMonitor and observe the clock speeds (and core temps!)achieved while opening/closing assorted applications, observe what clock speeds and temps are shown. (You should see speeds fluctuate as low as 800 MHz while just staring at a desktop in an idle condition, with instantaneous jumps to as high as 4.1 GHz, back to 1000-2000 MHz, etc., as you open/close apps and use the computer. If stuck at 800 MHz, something is indeed wrong...
I'd also consider a full fresh install of newest WIn10, installing only the apps you use/need, and leaving all of Dell's junk off of it. Better yet, grab an SSD first, and install fresh to that. (Not sure if your mainboard supports NVME/M.2 drives, but, even an 860/870 EVO or Crucial MX500 would make a night /day difference in bootup speed to the desktop)