blocks have delayed reaction to mining them with tools in survival mode.

Usually when mining in survival mode with tools the blocks, when destroyed, become loot drops that pop into your inventory when walking over them.
yet lately the blocks stay in place for up to four seconds before disappearing and popping up as loot a few blocks away.
I've searched through the bugs and found a few similar issues and followed steps taken by the other miners with no affect whatsoever. steps I took were updating graphics card drivers, checking hardware and system performance of pc and all is fine there, its only minecraft doing this strange glitch. I've also played around with the video settings lowering the graphics options but still the same glitch.