Hashrate achieved fluctuates with no change in settings

[cphine]

I am new to mining and am currently participating as more of a hobbyist using only my CPU to mine Monero and Electroneum with Mining Pool Hub. My question regards the extreme fluctuation I receive in my hashrate using xmr-stak-cpu. I will post my details below, but in a nutshell, I will sometimes begin the program and hash away at an average rate of 300 h/s. (285-320 h/s) Other times I will start the program and it will only hit about 125 h/s. Restarting my PC doesn't seem to have an affect on this. I don't play with my settings (I leave them because I know they will hit that 300 mark) and I don't have other programs running simultaneously. My internet speed is about 50 mb/s so that shouldn't be an issue.

These are the reported rates by xmr-stak, not MPH since I know the rate they show is based on accepted shares in a given time period.

I am using an i5-8600k processor (not overclocked) and am using three cores, with one set for low power mode. This seems to consistently be the best as it uses 50% of my total cpu and with 9mb of L3 cache, this setup uses 8mb (If I understand low power mode correctly). The "no prefetch" option seems to work better set at true and the "affine to cpu" definitely works better set to false rather than specific cores. Again though, this question is less about the settings and more about the lack of consistency I receive with these settings.

I guess my question is, are these daily fluctuations just a normal part of mining? Are they being affected by the pool I'm mining with or are there perhaps settings on my computer or in the program I'm unaware of? I did enable large page support using the group policy editor so I'm not getting the memory errors and it did significantly boost my hashrate.
Below are my settings in XMR-Stak. Any help or explanation would be greatly appreciated.
Cheers,
Christian

"cpu_thread_num": 3,
"cpu_threads_conf" :
[
{ "low_power_mode" : true, "no_prefetch" : true, "affine_to_cpu" : false },
{ "low_power_mode" : false, "no_prefetch" : true, "affine_to_cpu" : false },
{ "low_power_mode" : false, "no_prefetch" : true, "affine_to_cpu" : false },

],