File size doesn't mean anything. It's all about the resolution of the image. Resolutions should be square, and multiples of 2, eg: 512, 1024, 2048, etc.
To me it looks like you are mapping a very small portion of the image over a large surface area. (I assume that's a wood texture, and the grain is too big for the object) Perhaps by scaled down UVs.
Imagination is more important than knowledge.