Fps gradually decreasing

Hello everyone!

Recently, my Minecraft has been doing something strange. I noticed first when I was using shaders. The fps was decreasing... slowly... and even tough it bothered me, I decided to try to forget about it and think that it was only some sort of shaders bug. But when I was playing without shaders, this thing happened to me again. And I am genuinely concerned now, because originally, Minecraft with shaders had around 200fps and now it's barely getting a 100 and sometimes is getting under 60fps. Can someone help me on this matter please? Is it some sort of well-known bug or is it something I'm only experiencing? And if it is well-known, is there a solution?

Thanks!