Custom Input Field

Okay, so I am in BIG problems.

How to create custom Input system? Unity has lots of limitations, like you can’t add your own functions (CTRL + Delete, CTRL + Arrows), basically lots of features that many text editing tools have. Text Mesh Pro is just glorified Unity stock garbage with few extra ticks. You cant edit caret look or width much.

I have created my own input that has ALL of those features, has my own caret you can change whenever you want. Its like full blown text editor in game. It was pain specially with some special features or moving caret at specific position. BUT, THERE IS BIG BUT! Works on 300+ frames. When i lock game to 60 fps maybe like 40% key presses get recognized.

So my question is how to do this? I spent so much time on this text editor, fixed so many problems and shit and now run into this. Is there workable solution, like some text mesh pro settings or maybe asset store text editor. Or I should just abandon the project cause Iam tired of this shit. Why I need it? Its game simulation of OS and you need to use text editor for game to progress. its main game loop. I need these advanced text editing tools and need customizable caret.

TL;DR How can i send input (chars or string) to game from my keyboard that works even under low FPS.