Different export time under the same conditions

[Андрей5E17]

I switch my PC on, wait for it to fully load, open Premiere Pro (2022.3.1), open my project, export it. The export time is 8-10 minutes. I open the exported video to check it, find a video editing mistake (a clip was improperly cut). Then I have to go out so I switch off my PC. When I return I again switch on my PC, wait for it to fully load, open Premiere Pro, open my project, correct the previously found mistake, export the project. The time of export is more than 40 minutes. 

Yesterday when I exported another project the time of export was 10 minutes but I deleted the video file by mistake and had to export again. I did not start any other programs, did't open Chrome to brows the internet and did not even play the music on my PC, did't do anything that could load my PC! Literally - I exported, deleted the exported file (by mistake) with Premiere pro still on, and exported again. The second time the export lasted 58 minutes. 

Can someone explain why this happens?

[Richard M Knight]

I had an issue where Premiere sometimes started without the Cuda acceleration, a restart often fixed it.

[Андрей5E17]

It is funny, but after a 50 minutes export just now I added a white
background to another video element so that the screen gets split and
exported the same file again and this time export shows 9 minutes. No cuda
change, no restart. I don't know how it works or what it's connected with...

[Peru Bob]

What programs are running in the background?

[Андрей5E17]

None except for an ordinary pack (antivirus, nvidia, realtek audio etc). I
have 32 Gb of Ram, Core-i7 and NV 1060 6Gb plus the whole adobe pack is on
an SSD). It is not because of my PC specs, I assure you