BLOCKS NOT SHATTERING

this may be related to the laggy issues i recently issued. at times, when I use a tool on any blocks, it either takes a long time to shatter or it takes two times to go through it. example - when I use any pickaxe on a stone block, it will shatter, but reappear. i will have to use my pickaxe on it twice. not sure if this contribute to lessening the durability on the pickaxe, but if it does, this is a major issue.