Buggy chunks

First of all, my computer is not buggy,slow or anything like that. Its just average, not so powerful. In minecraft, got fps of 42.3 average with rendering distance as normal and smooth lighting minimum plus fancy graphics. With full graphics (but not far as render distance due to java bits problem), got fps of 25.6 fps average.
About chunks, they load so fast but when add things and modifications to map, the fps (or the chunk loading) gets slower a bit ,especially due to moving things and powering circuits.
In the first of two screenshots, there I shows the chunks load so slowly. In the other screenshots, showing the limiting earth i.e all chunks BECOME VOID just like I am playing Pocket Edition. This happens for the first time that the world got limiting from all ends and become squared! Minecraft has so many bugs related to chunks. Hence, all I want to say is to optimize and improve the chunks and its loading!