Your WinMTR shows two routers (192.168.1.1 and 192.168.0.1). Not likely to be the cause here, but undesirable. There's at least 1 ping spike to the 192.168.0.1 router, which is odd if it's on the local network.

I've not seen you mention reinstalling TF2 (and starting completely stock first, no fancy configs) and reinstalling Windows, try those, in that order.

I see you've tried using your PC somewhere else and getting the same problem, but still, can you describe your network setup? Is it a true ethernet connection or something like a powerline adapter? Because those are almost as unreliable as wifi for gaming. What router(s) are you using? How are you connected to these routers exactly?
What kind of network adapter do you use in your PC?

Judging from your video, something happens causing you to receive less packets (see "in" packets/sec drop below 66 when it lags), but at the same time you appear to receive more data (see the "in" k/sec). This is counter-intuitive, but could make sense if these packets arrive out of order or are somehow corrupted / unusable.

You tell me, please :)

Machine ran out of disk space, fixed now :)

The max CPU and GPU temps in those screenshots aren't from a game/loaded state. Make sure HWMonitor is on during your game and check the max temperatures after you've experienced those 40FPS drops.

Do you get the same drops in a synthetic benchmark like Unigine Heaven? If you're playing in windowed mode, does switching to fullscreen mode help?

Depends on the results of the test. Personally, I hope people won't find 133 tick a big improvement since it will increase the CPU load on the servers and I have serious doubts that my two 12-core machines can run 133 tick all the time for 6v6, let alone 9v9.

It's really easy to view the server tickrate (net_graph 5 in the client), so it would be hard to do a blind test.

Check if the modem has a firewall log, some go into a blocking mode if they detect portscans (even outgoing).

Whenever you open the TF2 server browser or Mumble server list, your PC will send out a bunch of UDP packets trying to get info on the servers, some stupid devices with built-in firewalls consider this port scanning and will block connections for a while.

The point is reduced transmission times and fitting all packets within sv_maxrate, it's a trade-off. The time you lose (<0.02ms) to compress a packet is gained by having to spend less time transmitting it (because it's now smaller).

I'd stick with the defaults (both client and server) over lists of TF2 client and server cvars with no data/benchmarks.

We're talking kilobytes per second here, this will not cause >1% CPU load on any CPU made since TF2 was released. Also, only large packets are compressed (net_compresspackets_minsize).

I've modified 3 EU serveme.tf servers to run at 133Hz:

133Hz - BolusBrigade #1
133Hz - BeretBrigade #1
133Hz - KroketBrigade #1

Just tick "Enable plugins" when making your reservation.

Ah, this is obviously some strange usage of the word 'free' that I wasn't previously aware of.

Was excited for a little bit, thinking NA would get a free, well-run, prestigious league option to give comp TF2 a boost, instead it got slightly less expensive, which won't do much, if anything.

That free market was carefully carved, divided and swapped by the US telco's to create local monopolies back in the "summer of love".

Services that compete with products from your ISP will be blocked or throttled. This is not hyperbole, it has already happened wherever there are no strong net-neutrality laws, including the US as recently as 2013.

http://etf2l.org/2017/11/17/happy-birthday-etf2l/

Verify your build and software installation is OK by running a benchmark like Heaven and checking your scores against similar builds.
Your build should be more than strong enough to run TF2.

I will title this "When you do your AC task so well the cheaters still insult you after you're gone"

Good job Miggy

Thanks to the family for allowing us to participate