Mouse double-clicking and unable to hold ONLY after playing Terraria

[Cowrocks]

God I love this game, but 1.4.4.9 seemed to start doing something really strange. I noticed around December 2022 after my friends and I started a new playthrough that after playing some Terraria, my mouse would start acting up. It would double click instead of clicking, and it could barely hold click. As someone who plays a ton of FPS games, this is so irritating. Is there even a fix to this?? Why does it even happen?? This happens to TModLoader too.

[Smetrix]

Maybe your mouse is broken lol? The fact that you were playing Terraria when it occurred strikes me as nothing more than a coincidence.

[EddyBrocklyn]

I have this when I turn all options ON. I think it's fps thing I noticed this when it's raining & I want to place something into frame, it double click, turn all to minimum/ low/ off & frame Skipp ON...
Sometimes can double click,but it's so rare and only if I play long in world and allot of items in world.
All effects make it lag and double click

[Recondite]

Assuming your mouse is working 100% properly and you have no other issues in any other games: in rigidly-serialized games like Terraria, those symptoms are usually caused by a missed or skipped frame and/or by the interpolation logic used to correct for that issue - which is thankfully pretty easy to troubleshoot. If the problem persists without any change in behavior AFTER you stop playing Terraria, but goes away after a reboot, I'd strongly suspect #2 and #4 below, in particular; otherwise, turning Frame Skip OFF and manually capping fps to 60 at the driver level—and that's 60 specifically in Terraria's case, regardless of native refresh rate—might fix the problem entirely IF you never struggle to maintain a constant 60 fps, but if your system can't manage that with in-game graphics appropriately tuned and/or if that alone doesn't help:

1) Proper base game config: After ensuring Frame Skip is OFF, make sure you're running in true fullscreen mode rather than windowed/borderless, as Terraria's framework is more or less incompatible with the dynamics of hybrid fullscreen and similar schemes (e.g. Windows DWM). If you play with vsync on globally, explicitly turn it off in Terraria's driver profile and manually limit fps (preferably with RTSS for best efficiency + the option of scanline sync). You can also try manually setting pre-rendered frames to either 1 or 0 in Terraria's driver profile, but that's only likely to help if other system problems are contributing factors or if your system is severely underpowered for gaming (e.g. laptop and/or integrated gpu).

2) Test with mouse profiling software disabled if you have any (and make sure to kill its services, too) to rule out a corrupt profile or profile-switching issue. Having a polling rate too high also commonly causes clicking- and holding-related mouse symptoms in these kinds of games, so be sure it's not set higher than 1000 (at the absolute maximum).

3) Disable Steam overlay and any other software overlays (Epic, Origin, GeForce Experience, RTSS OSD, etc) to rule out their numerous input-related conflicts and bugs. If you use it, GeForce Experience is a particularly common source of both performance and input problems in many, many games, so make absolutely sure you test with it completely off. If you use RTSS OSD and it seems to be the problem (unlikely in this specific case), test with Terraria's app detection level set to Low, and you can also try toggling stealth mode.

4) Playing on W8/10/11? Disable all Aero & Transparency features globally, and (IMPORTANT!) activate the compatibility flag to disable fullscreen optimizations (desktop composition) for Terraria.exe. On some systems (highly dependent on hardware and especially dpc latency), setting Desktop Window Manager process priority (dwm.exe) to Above Normal may also help. Note that W11 in particular still has numerous bugs affecting fullscreen applications on a wide range of otherwise perfectly-capable hardware, and likely will for years to come; nothing you can do about that yet if you're affected, except revert to the last version of W10 that wasn't completely awful (1709).