first of all i like that people try to help each other, in order to make it possible to play the game. however it doesn't help anybody to spread misinformation and will just mix all the useful information out there with nonsense, which will make the process of finding real help for any new and unexperienced players a real clusterfuck.

first of all there are a ton of parameters on your system, that will influence your computer's performance. the most obvious one being your hardware itself. if you really try to play the game seriously without sucking major D, you have to get a decent setup, period. sure, you can adapt to insane input lag over time, but that doesn't change the fact that you will still put yourself at a huge disadvantage in competition.

input lag is basically the time that is ticking away between an action that you execute in real life, until it is seen on your monitor. it's basically the counterpart to reaction time (the time that is ticking away between something you perceive [with your eyes or ears] until you perform an action). both, input lag and reaction time, hinder you from performing well, cause they add up. while reaction time is (by its nature) something you can only slightly improve with training, input lag is something you can actually put to a minimum. input lag is measured in milliseconds (thousandth of a second), but since there are so many processes adding up to it on your computer, it can easily get up to a few hundred, which will have a pretty big influence on your performance, even if you think it's not a big deal (not to mention all the other visual and technical impacts). in the ideal case you want input lag to be 0 (which is physically impossible) in order to make your actions (performed with mouse and keyboard) 100% in sync with what you will see in front of you.

you can imagine having much input lag with being dead drunk. every human being has a certain reaction time (just accept this as a fact since i don't wanna go into detail too much), that is different from person to person and only lightly improvable with training. the average human reaction time is about 250ms; describing the time from when you perceive something, until you can actually react to it with action. being drunk adds a shit ton of input lag to your actions, which will result in you being unable to perform certain actions, that would seem easy without it (catching a ball, going in a straight line, etc.). briefly speaking it's something that you can lightly adapt to, when you do it often enough, but overall it's still a very bad quality to have.

things that add up to input lag are network performance and latency (ping), frame time (correlating with fps - and there are just too many things influencing your fps to list them in this "short" post), mouse processes, keyboard, monitor, video settings, display driver settings and last but not least your very own reaction time.

as you might see, there are quite a lot of things, but explaining all of them would simply take a lot of time and space to describe. and since most of you won't read this annoyingly long post anyways, i would just waste my time. if there are enough people, who are interested in learning more about the input lag and similar factors, i would be willing to make a guide about it and explain everything concerning that whole matter a bit more detailed in an ELI5 manner. or if you have a specific question just feel free to pm me.

launchparameters: "-no3d9ex" doesn't do anything on csgo. period. "-threads 4" is useless as well, since the csgo app should usually utilize 4 threads by default (when on multicore cpu with enabled multicore rendering in options). don't know about "-high" though, it didn't do anything for me (like task priority never did), but that doesn't mean it isn't a factor on lower end computers. after all your fps are not only influenced by your hardware and the video settings, but by many different software parameters, driver compatibility and driver settings that you are unaware of. some people just overdo the tweaking part of the matter, simply cause they pay more attention to matters they didn't earlier... it's called placebo.