I played it a month ago on Ubuntu 15.10 and it ran pretty poorly. I messed around with settings but I didn't get anything near the 120 fps I get on windows. I reached maybe 30fps if I remember correctly.

Hopefully you know to run nvidia, not that a gpu matters that much for tf2

As a linux mint user, first thing I'll say is if you run any mods other than a hitsound and hud you better get rid of them as more than 2 mods in your custom folder causes crashes on the stricter sv_pure servers (i.e. valve servers)

In terms of performance, in order to get decent frames in battle I had to use comaglias config, running a i5-3570. Based on what I've seen performance is about 10%-20% worse than windows with a good rig (intel+nvidia) and awful on anything else. No stuttering or any unplayable issues, its just the linux version is definitely not optimized right now, have no idea how it compares to windows performance though as I haven’t booted windows at all this year. At least valve intends to optimize this game at some point

Feels bad knowing how bad tf2 runs now compared to when the linux port came out, it ran and loaded way faster than windows tf2 then, now its a caught up with windows and then some.

Edit: one thing I will say, is when I upgraded my kernel from 3.19 to 4.2 a few months back I got a noticeable performance boost in tf2, so I'd probably run a distro that runs more recent packages, or the debain sid repo in your case. Might have just been a weird case with me though

I've played on Linux (Lubuntu 15.10 currently) on my laptop for the last year or so with an i3-4010U. Using Chris' maxframes, I normally average a decent enough fps, but particle effects and such can definitely drop it into the single digits for me. For the most part, I've never found the game to be unstable.

Arch on my laptop with an i7-4700MQ and GTX765M and comanglia's config nets me around 80 frames with bumblebee. Windows 8.1 with the same settings gives me about 150 fps.

I play on Arch with an FX8350 and GTX570. I get good enough frames with comanglias config and proprietary drivers. It's definitely worse fps than on windows, and frame drop issues happen a lot more.

I haven't gotten matchmaking to be playable yet, I have huge stuttering issues with the settings it forces.

Edit: CSGO runs perfect for what its worth.

#3 Yes I've heard linux has terrible AMD drivers, or something. It seems like the people with bad frames were using 'bloaty' distros. I guess I'll be fine with Debian and new packages. At the very least I can have a windows partition where I disable updates on first launch. Anyway I'll contribute with my hardware etc. when I get it running.

Im on arch, X crashes whenever i join a hightower server.... pain in the neck

i get about 75% the frames of windows on arch and a phenom 2 x4 and a radeon hd 5770 with mesa

Playing in Opensuse Leap with an R9 380X and an i5-4690K with Comanglia's config for max fps.
I get over 300 fps normally and over 200 in MM. Generally, I get better performance than in Windows.

Arch, i5 4460 + R7 250X (thanks setsul), game plays between 150 - 200 fps on Comanglia's "Max FPS for High Quality PCs" config. No unexpected crashes

Matchmaking frames aren't that good (usually <100) due to the config forced by TF2 + AMD's shitty support for Linux >_>

Gentoo user here.
TF2 runs without any crashes, on stable 300 fps. No pain when it comes to dx8/9 choice (OpenGL FTW), KBNHud supports Linux perfectly. Now the only thing I miss is prec.

When I run the game under windows I get about 50-200 frames, where 50 is usually in pub mid fights. When I run the game under linux(ubuntu) I get half of that. I am running on a laptop so that might be why it's quite slow with following specs, i5 2410m and GT555m

I have both Windows 10 and Arch on my laptop, and I seem to get about the same number of frames (~70) on both. Matchmaking sometimes makes it crash on the first game I try to connect to, but after I get started it usually works smoothly. Also on Arch tf2 takes about 4 minutes to start compared to about 10 seconds with windows, which I don't quite understand.

Arch linux with linux-ck kernel patch and multicore rendering turned off in tf2.

I probably get ~50-100 more fps than I do in windows

a question for you linux users than if i got this thread here already.
if you played on winows before that do you notice any differences in mouse speed? even when i was 100% sure that my drivers were working correctly, my mouse felt about 1.5 times as fast even on desktop while not ingame.

There's no raw input afaik and some distros have mouse acceleration so this would be my bet

I got Steam working as per the Debian wiki and installed tf2. I have yet to purchase a GPU as I'm waiting for a good deal, so I'm just running on an intel i3-6100 and integrated graphics. It's my understanding that all drivers were included in the kernel so I haven't installed anything but xfce and chromium. I didn't expect great frames without a card but on my old laptop I got ~120 fps on a local server and that was an older generation i3 with integrated graphics.

TF2 hardly runs at all. I'm getting like 5 fps in the main menu and even loading the map took ages. Surely something is configured wrong and it's not the hardware/linux, right?

I regularly switch between Arch and Windows 7, so I have a fair bit of recent play time on both platforms. I personally don't notice any differences between them, they perform similarly.

 OS: Arch Linux 
 Kernel: x86_64 Linux 4.4.6-1-ck
 Resolution: 3840x1080
 DE: XFCE4
 WM: Xfwm4
 CPU: Intel Core i5-3570K CPU @ 3.8GHz
 GPU: GeForce GTX 760 361.28
 RAM: 7875MiB

I use the ck patched kernel and proprietary NVIDIA drivers. I set CPU policy to SCHED_ISO when running TF2, and the CPU governor to Performance. I use an unaltered cowmanglia's gfx.cfg and run the game at 1920x1080.
Running this "benchmark demo" gives me the following:

2639 frames 18.378 seconds 143.60 fps ( 6.96 ms/f) 11.731 fps variability

Windows with same cfg for comparison

2639 frames 19.202 seconds 137.44 fps ( 7.28 ms/f) 10.304 fps variability # dxlevel 95
2639 frames 19.222 seconds 137.29 fps ( 7.28 ms/f) 10.262 fps variability # dxlevel 90
2639 frames 16.815 seconds 156.95 fps ( 6.37 ms/f) 11.132 fps variability # dxlevel 81

There is raw input, it's simply bugged. TF2 has a bugged version of a library that doubles the raw sensitivity. Using half your Windows sensitivity should be identical.
Disabling mouse acceleration is always good though.

I have a question: How well does TF2 run in SteamOS compared to other linux distros?

I heard that SteamOS is optimized specifically for gaming.

How big of a difference does the linux-ck patch make? Can anyone explain why disabling multicore rending would help? I'll try it out later.

That's correct, it's an old version of SDL that reports all inputs twice, so doubles your sensitivity. CSGO has had this fixed for a while afaik. If you want, you can load a newer version of SDL before launching the game using LD_PRELOAD I believe. You can put this in your launch options, example here.

I've been on and off different Linux distros for a few good years but have stuck to Ubuntu 14.04 for at least half a year now with very little Windows use. Honestly, it plays fine. To me, at least, there is no huge difference between Windows and Linux in my TF2 performance, but YMMV.