Guess not, the ping spikes are still there...

Ok, so you were... half right with that?

I'm not too sure why, but for some reason the "cl_updaterate 66" setting didn't actually get transferred to the main config.cfg file, whereas every other setting in the autoexec.cfg did. So it wasn't an issue of "the values are being overwritten", but "the values aren't written at all, even though they should be". Even manually adding it to config.cfg just made it disappear again after launching the game.

So manually adding that line and then setting the file to read-only did the trick, my lerp is now 15.2ms, as it should be. I didn't have that much time today, but of what I played so far, the ping spikes seem to be gone as well now, which is nice.

Thank you very much for the help, really appreciated.

Yeah, I just checked, there's no command lines that change any of the above settings in any of my other config files... :/

Fairly positive that none of my class configs change any of these settings, but I'll have a look when I get back from work. Thanks though

So while I'm playing on any kind of server, I keep getting ping spikes for around 5 seconds. They happen pretty frequently, probably one every 2-3 minutes during which my ping jumps to 150-250 while I have a ping of 20-30 normally. Also, this has only been happening after the jungle inferno update hit and only on TF2.

Not sure if this is related to that issue, but my lerp also seems to be constantly stuck at 50ms (and is displayed in orange), any .cfg files I created don't do anything to change it.

My autoexec.cfg has this:

cl_updaterate 66
cl_cmdrate 66
cl_interp 0
cl_interp_ratio 1
rate 60000

Any idea why these two things happen and/or if they are related?

I'm not sure if this is connected to the bugged inspect animations you've mentioned, but hiding primaries for Pyros will make it play the inspect animation for primaries over and over again if you do not have those hidden.