Have you noticed other games running slower than usual? If so it is most likely your system or hardware.
Are other servers running better? If so, then I can't help and you would be better off talking to olympus staff/devs etc. (obviously).
Are the temperatures good while playing Arma? No overheating?
Have you installed anything unusual lately? Run a virus/malware scan?
Haven't cleaned out your pc software in a while? CCleaner, temp files, etc?
Did you try rolling back your drivers at all? The new updates might have effected your FPS.
Change your Arma3.cfg or .Arma3Profile any? Increasing your FOV, changing GPU_MaxFramesAhead, GPU_DetectedFramesAhead, might have hurt it.
Are you running Arma 3 on an HDD or SSD?
Changed any launcher options?
Windows 10 DVR off? Sometimes it likes to turn on randomly every couple of months for me, I just keep it off. Heard it helps with FPS but I just didn't like the feature.
My FPS in Arma 3 tanked and went from like 50 fps to 20 fps before my graphics card died. Could be a sign of some failing hardware, however, your equipment wasn't as old as mine was. My guess right now would be some driver issues since @Vigi easy money has the same specs as you and had problems.