Talking

@BoneChi11er Sometimes its just a problem with the shader pack. I also have some shaders that don't correctly. You could try to change somesettings in the shader pack options. The version is not always correct because i'm also running shaders from version 1.8.8

@Qfu vry thrustworthy

@iDogeTwinkie do you have the steam version or the rockstar version?

@iDogeTwinkie I have GTA 5 on PC. Ask me any time if you want to play it. Never really played it much because I don't have friends playing it :P

@Retrochewy Shaders take a lot of PC-power. For example:
I can run Minecraft (when standing in my base) at ~700+ FPS (on Linux Debian I sometimes hit 1000 FPS (idk if it makes any diffrence)). That is with 16 chunk render distance and everything else pretty much on fancy and with 4x FXAA (which is anti-aliasing).
When I enable a shader pack (in this example an ultra shader pack) it drops down to ~70-100 FPS. I can run pretty much any ultra shader pack at 60 FPS or higher at these settings. But there are 1 or 2 that go under 60 FPS. With those I also need to start turning down settings.
Even when enabling low quality shaders it can still drop ~500 FPS for me (not exactly sure).

When you can only run at 40 FPS you probaly cannot run any shaders. MAYBE a very very low quality one. But I don't think it'll work out, unless you want to run at 10 FPS.

This is with an:

CPU: i7-6700k
RAM: 16GB
GPU: GTX 1070

Meme

@R4iscool1 basically explained everything. Its just that Mojang doesn't bother to change the way vanilla servers work.
While you could also switch to a Spigot server with no plugins and that stuff you will have almost no lag (most likely) with the current hardware we have, but then it wouldn't be 100% vanilla anymore.
Personally I didn't notice a great improvement when we switched from an i7-6700k to an i7-7700k, but the 7700k isn't that extremely more powerful than the 6700k. So this is probably the best performance we can get for a while.

@LordPanfer when in the launcher go to game options (its the tab all the way to the right, idk whats it called again). There you can make a new profile or select the current one you have. Once you did one of those go to "select version" or "game version". Then select version 1.12 from the list. After that just go to the main page/tab from the launcher. Press the arrow facing upwards and select the profile that you just changed/created. Then just hit play.

@Qfu