Your problem could be cpu usage too high or not enough ram causing too much hdd/ssd io activity so it is considerate to include specs and help those trying to help you.
List specs plz and share some background information on whether it was ever good before?
How are you monitoring fps? Have you tried Vsync to synchronised frames to prevent frame skips?
GPU: Gigabyte Radeon R7 240 2 GB GDDR3
CPU: AMD FX-8320, 3.5 GHz
MOBO: ASRock 970 Pro3.0 R2.0 (or 990FX extreme3, i don't know)
HDD: SATA 1000GB (not sure what the exact model is)
RAM: 2 Adata sticks 4 GBs each
PSU: Cooler Master RS-600-ACAB-M2
also i am monitoring fps and usage through MSI AfterBurner. FPS doesn't seem to go down, it just looks very laggy. Usage also stays exactly the same, and I have tried the same with shaders and different versions. the FPS seems to fix only when I load 1.8. Also, I have tried VSync, it doesn't change anything