How to make texture editing without any lag ?

[GamerDreams2019ns]

Hi,

Texture editing a 10x10 map is not a problem but texture editing a 20x20 map then my pc Hdisk kept on reading (lit on non-stop) and this caused the map editor to slow down almost to a halt.

Turning off layer (make it hidden) and turning off the water effect did not help. Any thing I am doing it wrong ?

Thanks.