The launch options were
-freq 144 -novid -nojoy -nosteamcontroller -nohltv -particles 1 -NoQueuedPacketThread +cl_clean_textures_on_death 1 +mat_lodin_time 0

As for mastercomfig version, I've been using the 8.5.0 but have also had issues on previous versions. The addons I use are the pyroland, flat mouse, medium-low, no extra models, no soundscapes, no tutorials, and null movement.

I've also had this same issue without the launch options, and without some of the addons.

SKEEZ

All the parts in my PC are pretty new. (8700k, GTX 1080, 16gb 2400mhz RAM from last year)

I realize there are a lot of old threads about similar issues, but I couldn't find any that were close enough to mine. After playing TF2 for like 20-30 minutes, I notice that my mouse input begins to lag and my framerate goes down slightly (from like 300 to like 250). I've had this issue for a few years and have never been able to figure it out. I've fresh installed TF2 multiple times, used different mice, and this problem has persisted over a few different CPU's and GPU's. I'm not sure if I'm going crazy or not, but there is a noticeable increase in mouse input delay after a while of playing. If I restart my PC, it goes back to the normal buttery smoothness for a little while. But, just restarting the game doesn't seem to help too much. I've tested for overheating and other things like that but temps are all okay, it also doesn't seem to happen in any other game. The people I've talked to have suggested it could be a memory leak, but I'm not really sure what could be causing it.

If it helps -- I use default tf2 HUD, Mastercomfig stuff, DX8.1, 144hz, and Fullscreen stretched 1024x768. I can add more info if needed.
I would appreciate any help or suggestions so I don't have to restart my PC after each half of scrims :)

UPDATE: SEEMINGLY FIXED--
It seems to be fixed now. From what I can tell, the issue was with my SSD and my OS. I fresh-installed Windows10 onto my HDD and the issue is completely gone for now. Figured I would update this in case anyone else has the same issue in the future. Just move your OS from your SSD to a different drive and it should fix. Thanks for everyone who tried to help!

UPDATE: I lied, see below.

bump, still looking for some tryouts

Found team :)

Sorry to somewhat necro, but I just got messaged by this user: https://steamcommunity.com/profiles/76561198263086940/
asking me to help his highlander team with a tournament with a prize. He linked me to a site named "peace game it . com" and gave me directions to sign up for his team. Obviously a scam, I pretended the link didn't work. I also googled it and the website did not exist. He then started to confusedly message me, asking if I was using Kaspersky antivirus. I told him he was an idiot for trying to scam people and then he blocked me.

Figured I would at least add a name to the list for people to watch out for. Always assume random people are trying to scam you when they link you stuff.

edit: put spaces in the link so people don't click on it reactively

Cool to see so many people offering help! Definitely feel free to use this thread to find some coding help.

.

I would recommend reverting your drivers back an update or two instead of reinstalling the same ones
edit: and as always, verify game cache if you haven’t already

There is a separate section dedicated to name changes and stream additions. Would recommend going there instead

So I fresh-installed, used m_limitedcapture_workaround 1 and did the Disable Fullscreen optimizations and my tf2 is buttery smooth again. Not sure what the issue was though, will update if it occurs again.

That's what the MarkC Mousefix is for. It's off in the Windows settings but due to the mousefix, it shouldn't matter anyway. And like I said, it only happens in TF2, so it must be a setting local to that.

It's not so bad that it'll affect my rocket jumping, but it's nice to hear I'm not the only one having issues. Mine just feels like I have V-Sync on but I know for certain that all V-Sync settings are off

I feel like there's 1000 of these threads, but I couldn't find one that was close enough to my problem and didn't want to necro any old posts.

Ever since the large-ish update a few weeks ago (April update with the MM changes and all that), I've had some pretty annoying mouse input lag. It's not enough to be a HUGE unplayable issue, but it's bad enough where it seriously bothers me and alters my aim quite a bit. Yes V-sync and Mouse Accel are off, I've done mark c mouse fix, re-installed about 8 times, turned off the controller settings (as far as I know), used different configs, different direct x levels and all that. It ONLY happens in TF2 and is perfectly fine in all other games as well as on my desktop. It very slightly gets worse over time, but theres no overheating happening. I've had a few times where it fixed after a clean re-install but it seemed to go back to being laggy after a little while. My framerates are almost always 200+ even in pubs, so that's not the problem either. I've had the issue in the past but it used to go away after a few months, this time it has not.
Thanks in advance for any help!

edit: I forgot to mention that my brother also plays TF2 on my PC (different windows account) and I'm curious even if the settings are the same across the accounts (minus like crosshairs and sensitivities etc) that logging into my account after he was logged into his could affect it in any way?

edit: Also decided to check CSGO since I haven't and the issue seems to be there as well. The only things I can think of would be: A source engine issue or a resolution issue (I play at stretched 1024x768 on both games)